After a lot of use, I have to say that in heavy turbulence, it moves a bit out of place and the grill is forced to fall downwards. Other than that, it is quite helpful as an accessory.

it's fine. but don't expect that the phone can't fall!

On a steady route, especially for long distances on highways, it's fine.

If you go on a road with potholes, let alone a dirt road, take it out before the phone falls and breaks.

The positives have been written by most below, I will write about a negative that I didn't see anyone else mention. This has to do with the charging speed and whether the phone is in a case or not.

I tried (with the same charger always), and if the phone is inside the original Apple magsafe case, it shows a slow charging indication (settings -> battery). If I take off the Apple case, then it charges normally. I would give it points if my case wasn't original (I would blame the case and not the base).

A huge downside for me is the slow charging, as if someone has maps, GPS, data, Bluetooth, etc. activated (which is reasonable when driving), it essentially offers nothing since the phone ultimately discharges.

Great upgrade, exactly what I was looking for. No need to stick magnets on the phone or anything. It uses the iPhone's MagSafe magnet and charges as well, what else could you want? Obviously with a very abrupt braking the phone will fall off, but expected.

As a charger and magnet, it is quite good. However, the hook that attaches to the air vent does not grip as well, resulting in the phone falling off along with the base.

I have it for about a month now. The magnet is very stable. Now, I still have some reservations about the frame. I want to try tightening it more. At this stage, however, it doesn't hold the phone up high, and luckily the radio screen is right below the air vents, so I rest it on top of it. But maybe it just needs more tightening.

Sturdy and high-quality. It has a strong grip and doesn't move from its position even in puddles (14 pro max).
You really need something sturdy for this phone...
Its neck gives you many position options with a truly stable grip. It doesn't move at all from where you put it. A really good purchase. It has been installed with the apple MagSafe case.

For the iPhone 13 Pro Max at least, the base is completely useless for its intended purpose. Unfortunately, the magnetic strength is not even remotely capable of holding the weight of the moving phone. (Considering that I have it in a genuine Apple MagSafe case.) I didn't even need to place the base in the car or unwind its cable. I stuck it (with the magnet) to the MagSafe case of the phone, held it by the "ball" (joint) it has at the back, and with a little shaking up and down, the phone would fall after a few shakes, while when I lightly hit my elbow on the table (like a car hitting a pothole, for example) the phone would immediately fall. Luckily, the store where I bought it has a money-back policy, so I won't lose the money at least.