After 2 months of use, I have identified only 2 negatives:
1) Sometimes the app on the phone "freezes" and does not update from the smartwatch data. Restarting the phone usually fixes it. Sometimes turning Bluetooth on and off on the phone also helps.
2) Because the smartwatch calculates an average (for pace and HR) over the last few seconds, it takes time to display the actual number. So, during intense changes in pace or HR, for a few seconds the numbers on the smartwatch are either higher or lower than reality.

To mention the positives, so far I am extremely satisfied with the pace 3. I load my weekly program, which I have set up as I want, the default GPS accuracy covers me in 99% of my workouts/races, and the battery lasts about 2 weeks (8-10 hours of running and 2-3 hours of exercises).

Also, two things have been very useful compared to before when I didn’t have a smartwatch: the sound notification when I am out of limits (pace/HR/thresholds/etc.) and the monitoring of sleep or recovery in general.

I think for its price it is a very fair purchase, especially for those who are amateur athletes in various sports.

Update 28/09/25:
Something that has happened to me 3 times and needs attention. If it is not properly placed on the wrist so that it is stable, then the HR can appear much higher than the actual value (according to Coros, it gets "confused" with cadence, see also https://www.snackinginsneakers.com/cadence-lock-running-watch/). I have had it show +25 beats because the watch was moving a bit on my wrist (especially with sweat, the situation gets worse). As soon as I tightened it (2 fingers above the wrist), after a few seconds the value dropped to the expected level. I think if one finger barely fits under the strap, it’s ok. It also helps before you start running to make sure the watch has given the ok for HR and GPS measurement.

And two positives:
Firmware updates are released often, which either fix various issues or add new features.
The glass seems quite durable. I have hit it accidentally several times and it has not shown any marks.

Update 23/03/26:
I also tried music with Bluetooth headphones, but I was disappointed with the data transfer rate via USB (max 355 KB/s). So make the necessary preparations.
I also consider it a negative that there is no way (at least I didn’t find one) to have a sound notification (the usual beeps) in the headphones, only a voice notification (which personally tires me with how much it says).
At least the music plays smoothly and without problems.

Another problem that became more apparent during data transfer is the contact with the charging cable. For some time now, it does not fit well, because when the watch is moved, charging is lost and restored. This is not such a problem during charging, but during data transfer it interrupts you and you have to start everything from the beginning. Since I found other similar reports abroad, it is probably a manufacturing defect by Coros. I don’t know if it’s in a specific batch or in general.

I will refer to athletic use as well as the use of health indicators, particularly in measuring HRV (heart rate variability). I have had it for almost 4 months.
Its athletic use is for measurement in football in open and closed spaces, in open sea and pool. In open spaces as well as in the sea, the GPS works flawlessly and locks on immediately. The measurements are very accurate compared to the Polar H10, which I wear simultaneously both in football and in the pool. Particularly at high intensities of 180-190 beats, the measurements were identical, which impressed me, as well as in the pool with slightly less accuracy compared to the Polar H10. I was a Huawei owner, known for the accuracy of its sensors, but this sport watch exceeds expectations. In the pool, lap and stroke measurement is accurate; I had seen reviews and chose it.
As for health measurements, I will mention sleep measurement, where I believe it has quite a good measurement of sleep stages and certainly detects awakenings.
Finally, the measurement of HRV for those in the know during sleep, which directly interests me due to a health issue, is very important because I use it with the HRV4TRAINING app to monitor both my health and my physical condition, my readiness for exercise.
I should mention that the watch has an excellent MIP technology reading screen, which I no longer want to change, and at 30 grams, it can be worn at night without noticing anything. Battery life, even with GPS for 1 hour every day, lasts over 10 days... always with always-on display...
For those who want AMOLED, calls from the watch, replies to messages, look elsewhere, but with half the days...
That's all...

If the FR265 had an MIP screen so it wouldn't lose half its battery lighting up useless pixels (since both watches have breadcrumb but no maps that require overly detailed screens), if it had a flat screen crystal that is somewhat protected by the watch's frame and doesn't scratch as easily as Garmin's curved one, if it had a newer heart rate sensor and cost half the price, then perhaps the most details that say Garmin's software provides, combined with the equally good dual band GPS of Coros, would make it a good alternative. Now it is clearly just a cash grab by Garmin and I wasn't keen on spending double the money just for a name.

From what I've researched over the last 3 months, the Pace 3 is truly one of the best smartwatches available today for someone who is athletic. It has activity profiles, measurement accuracy, and battery life that competes with the FR965, the navigation features of the FR265, and a price 100 euros lower than the FR165. In other words, it has it all.

Or almost all. As I am quite new to the smartwatch space, even though I've been running for nearly 10 years, I still have certain expectations about what a watch is, which sometimes makes me see the whole space as a circus. If you had told me until last year that I would pay 250 euros for a watch that is not made of iron and sapphire, has waterproofing only at 5ATM, and a battery that lasts about a week with 2 hours of GPS activities a day and 24-hour use (for sleep tracking, etc.) and that all this is considered good, I would have laughed for an hour and then gifted you a GShock for 45 euros to learn what a watch means. Of course, there are worse things, like paying 2 and 3 times for the exact same package (I'm talking about you FR265 and FR965), which is why, in this very tough market research of mine, the main competitor of the Pace 3 for me was the Suunto Race, with materials that indeed suggest a serious watch, but with a heart rate sensor that, as every reviewer I've seen agrees, leaks from everywhere.

So here we are, and the Pace 3 has arrived on my wrist. It is certainly not made like a Seiko 5, nor does it have the protective plastics of the DW5600, but its plastic body seems quite durable, like a Casio for 30 euros, and I've never broken a Casio, although I've tried. I must say that the product photo does not do justice to the silicone strap, making it look stiff and hard like a GShock strap, while in reality, it is very flexible and soft to fit any wrist. The only downside is the strap loop that has a tooth, which is supposed to secure it in the strap holes and keep it stable, but in reality, it just complicates its passage.

Regarding the software, after syncing the Coros app with Strava or Apple Health, the watch connects seamlessly with the phone (yes, even with an iPhone) and automatically transfers information from one app to the other as soon as a workout or sleep is completed. Overly user-friendly in this regard, it impressed me.

I hope it lasts me about 5 years of comfortable use. If what is said about Coros' good software support is true, I believe it will do just fine. In the end, however, I gradually understand that in this category we are no longer talking about a watch but about a device that mainly collects location, training, and health data, so for what it does, it is one of the most honest watches ever made. Therefore, I must gradually adjust my expectations for these wearables. In any case, the sports information it provides is more than sufficient, and its measurements have been flawless from what I've seen in these few days that I've had it. However, it will not replace my Seiko at night. That will only happen if I go crazy and give away all my wealth to get a Vertix 3 when it comes out. I will continue to keep my DW5600 in my bag just in case. Despite the "impressive" 10-day battery life with everything on that the Pace 3 offers, 10 days is not 7 years, and in a tough moment, it’s good to at least have the time and a basic stopwatch. The Pace 3 is one of the best smartwatches, especially for sports. However, it remains a smartwatch, and everyone must decide if they need something like that.

Update 08/23/24:

After six months of use and literally hundreds of workouts, the watch is definitely proving to be a beast. It has gone through quite a few bushes on trails, has taken dozens of baths in the sea (no dives, I'm not playing with fire yet), and has endured 1-2 moderate scratches on rough walls without suffering any damage at all. Indeed, like a Casio for 30 euros.

From a technical standpoint, it is still one of the best smartwatches for training/adventure IN GENERAL.
GNSS? Extremely accurate on all systems on (25 hours on 100% battery), unnecessarily precise on dual frequency (15 hours).
Heart rate monitoring? Excellent, the combination of strap, lightweight, and sensor makes it stick to the wrist and not miss a beat, comfortably suitable for heart rate-based training without heart rate belts and other additional accessories.
Battery? Still good, although the 6 months have dulled about 10% from the initial peak of the watch. In the charging range of about 35-85% (general lithium battery maintenance routine) with 1-1.5 hours of GNSS All systems on training per day, and 24-hour usage, the watch initially easily lasted 5 days and went for charging on the morning of the 6th, now it needs charging on the evening of the 5th after the workout, because it has dropped to 34-33 and sleep monitoring might drop it to 30-29%. A detail, but yes, it has lost that dynamic in 6 months.

Otherwise, the functions of Coros are flawless. Some that I use and one that is missing:
There is a map in the app, where you can map routes from asphalt to trails and send them to the watch to guide you during the activity. On the Pace 3, you don’t see the map on the watch, but you see the route and your relative location. Very useful, it has saved me in unknown cities.
Training programs: You tell the watch when you will run, which race, and what desired pace, and it gives you a complete program. The company often does promotional training programs through Strava with real coaches, so even more opportunities for training assistance.
The Greek language... The Greek language is still not supported on the watch and app. I have inquired about this, and due to work, but no. A minor issue compared to what the watch offers.

Which is now also available in colored editions (this purple one is very beautiful, if only we had it with the release, that is)... The watch remains at the top and has even increased in my appreciation instead of falling, as would be logical. The only competitor that might come close is perhaps the Suunto Race S, with a better heart rate sensor now and a battery that lasts longer in GNSS activities but not in daily use due to the AMOLED screen, classically. We can't have it all, not yet... So, last update on the review. The watch is worth infinitely, but it has been out for 1 year, so in another year, the next one will probably be released. Still excellent, but for how long?

Amazing in its category. For running, which is how I use it, it's excellent. I made a summary to help anyone who wants to buy it.

Pros of Coros Pace 3 for running:
- Excellent GPS accuracy
- Nice design, just like the Pace 2
- Outstanding battery life (up to 38 hours) [I tested it on routes up to 30 hours over 2 days and it easily held up, with plenty of battery reserve]
- Rich variety of running features
- Connectivity with Android/iOS

Cons of Coros Pace 3 for running:
- Touchscreen can be annoying in some cases (some may actually like the touchscreen)
- No NFC

Conclusion?

It is a watch for activities. That is its focus. Perhaps the best in its category and in this gadget. Don't expect to find fancy features like a microphone or replying to messages. However, all of this is reflected in the specifications, and anyone who wants to buy it knows that.

edit Oct 2024:
Still, all of the above applies, I just want to add that sometimes it loses track of its measurements momentarily. That is, you run at a steady pace and it tells you that you are going faster or slower, and after a while, it finds its way back.