Update after one month of use (31 July 26)
Well, I spoke too soon, it doesn’t suit me after all, I’ll get another one. I need an intercom to talk to my passenger, who also acts as navigator, but the way this one works, where you have to press a button to talk, I can basically only use it on straight roads (the sidecar doesn’t turn with one hand). The passenger has it more comfortably, but still, from the moment you press the button and it says "connected," three or four seconds pass before it actually connects and the voice comes through, so I always miss half of what they tell me and have to gesture "say it again." Damn.

If anyone else also wants an intercom, what you should look for is whether the device says that communication between riders/passengers is "full duplex" or, in Greek, "two-way communication." Unfortunately, although I looked at many devices, cheap and expensive, before buying this one, almost all the reviews, even for devices that have intercom, only talk about sound quality for music and mobile calls, which is a bit insane — I mean, if you don’t want intercom, why are you paying for intercom? Without it they’re cheaper. Anyway, I’m leaning toward the FreedConn T-COM SC or the EJEAS V6 PRO+ which have full duplex/two-way communication, but again the reviews don’t help me because while the FreedConn has nearly five hundred reviews, almost all of them are about music and calls. Do you get what I mean? And the Skroutz AI also doesn’t help; I told it "I want to talk to my passenger" and it said "yes, of course, let me suggest a polite opening line." Bless my AGI.

Anyway, I still recommend it for anything except intercom. Cheap, and it works for such uses. And for anyone who only wants occasional intercom, well, let’s say it does something. It also has good noise cancellation.

Original (30-31 June 26):
I got it for the intercom because I have a motorcycle with a sidecar and I want to communicate with my passenger without shouting. Unfortunately, for this job I don’t like it because you have to keep the intercom button pressed to talk, and it also has a three-to-four-second delay until it says "connected" (meaning you can talk). It’s like a walkie-talkie, but more awkward because of the delay. For the motorcycle rider it’s a bit inconvenient and even dangerous, since you have to let go of the handlebars while talking. I didn’t like it.

Otherwise, it connected to Bluetooth immediately without any problem, both devices on both phones, the radio works well, I didn’t try music sharing, and it’s easy to install without any quirks (although I have no experience with other such systems, this is the first one I’ve bought). I mounted it on the helmet with the clip, not with the Velcro because I don’t trust Velcro. It’s cheap, it’s light, battery life remains to be seen, it also has a little screen, and the noise-reduction software is probably good. I don’t go at any crazy speed either (with a passenger I go up to 50 km/h because if you crash with the sidecar the passenger has nowhere to hold on), and we have semi-open helmets but we have no problem hearing each other with the intercom.

One downside is the instructions, which are badly translated and tell you about buttons that aren’t shown in the diagram, but there aren’t that many buttons and you can easily figure out what to do (the M button to change mode from Bluetooth to FM to music sharing and finally to intercom, the button with the microphone to talk, and two buttons for volume, plus the on/off button).

The only really annoying thing is that every time you press the button it talks to you, but now all gadgets are like that, they don’t keep their mouths shut. Couldn’t it just beep-beep?

I think both I and my passenger will get used to it, and anyway I didn’t pay 300 euros a piece, I paid 30; for the money it’s good, get it. Now, if you don’t want intercom because you’re one of those who say your wife behind you won’t stop talking your ear off, leave it, but then leave the motorcycle too and get a single-speed bike to go around on your own haha. I go on little beach trips and rides with my girlfriends and we want to chat, we’re like French ladies. I’ll get a third one too so we have it when we ride three-up.

I've had it for over a month, good sound and the others don't realize that I'm on the bike. The connection is good and the radio I've tried works fine. The battery seems to last.
I've tried it with a second one to see if the intercom works.

Disappointment, but with so little money I don't know what I expected... In the first 5 uses it came off and fell on the road.

I have nothing to compare them with, as this is my first intercom! Excellent set and it connects to the unit very quickly