Whatever you give, you get for the money. I have had it for a year and a half, no problem with the cable, it may be an installation issue, I have no problem. The only negative thing is that when you talk on the phone, you don't hear as loudly with the visor open

I have had it for 1.5 years and I have already replaced the headphone set twice as the cable at the connection with the device is quite sensitive, resulting in one earphone not working. Now it has a new problem, the volume reduction button does not work. Unacceptable!

I have had it for 1.5 years and I have already replaced the headset twice as the cable at the connection with the device is quite sensitive, resulting in one earphone not working. Now it has a new problem, the volume control button does not work. Unacceptable!

I have had the device for 10 months, so I can say from my everyday experience the following:
It does exactly what it promises and maybe even better. It connects to the phone instantly, it never disconnects, not at all. The sound quality is excellent and honestly, when I speak, the sound is effectively filtered, so the person I'm talking to doesn't realize I'm on a motorcycle going over 100 km/h. The application is basic but okay, I rarely use it to set radio stations and it works perfectly. The battery lasts. And it lasts a lot. I charge it once a month without letting it die. The battery level information is given every time you turn off the device, so you are always informed.
Yes, it is waterproof. Last year, I used it extensively under flood conditions and it worked perfectly.
But why 3 stars? Because the button handling is simply bad. Although I could never say they are not ergonomic by looking at them, I feel desperate when I have to use them on the go with GLOVES. With winter gloves, forget it, it's hard to answer a call, turn it on or off. Even with light summer gloves, it's not easy. Especially the station and music selection... no. It's wrong.
Also, I have an issue (probably) with the size of the device. I installed it (very easily) on a brand new and unused helmet (Shoei NXR) and after 90-100 km/h, whistling noises start coming from the outside. I believe it has a lot to do with the size and aerodynamics of the Interphone, as such a helmet (quality-price) should not have such an issue with relatively few kilometers. Lastly, there is a lot of noise coming from the left side where the device is installed. However, I CAN'T BE SURE if it's the Interphone's fault or the helmet's. I will come back when I change it :)
Another issue is that the cable that connects to the device gave up after 10 months of use, so for days I could only hear monophonically, which is not pleasant at all as the sound seems to enter the helmet as noise from the outside. The replacement costs 30 euros, a relatively fair cost, just a little early.
And finally, the helmet may have been damaged at some point in the trunk, and since then, the base of the Interphone is a bit loose. Of course, it can be replaced economically, but with all these issues, you start thinking about trying another device that doesn't have these problems.
I haven't tried connecting it to another similar device as I am probably a lone wolf, but I believe it won't disappoint there either, as it delivers on its other promises and even better.
In conclusion, it is good for its price. Sound, microphone, software, all good.
Ergonomics, nope, unless you are without gloves, then it's worth every minute of the 140 euros it costs.