I have the T2C and got mixed feedback pretty much along the same line as above. The bluetooth tethering was added after I received mine so it was a very positive surprise like a holiday gift. But since Apple Music became a built-in feature of Tesla, I depend on the T2C much less, to the point I just left it in the center console disconnected.
The connection was mostly stable in my case. The only time it disconnected was driving to Big Sur where there was no cellular coverage on my phone or on Tesla itself either, and even so, the car and the device seemed to try their best to restore connection without my help. My biggest problem was that the connection between the car and T2C was too persistent, even after I left the car. Since I didn't put a SIM on it, more than once the car was still connected to the T2C WiFi minutes after I walked away, and somehow it didn't lock, and I couldn't initial lock command from the app. I also got outdated vehicle status (door showed open on rainy days when it was actually closed).
Hope they will continue to improve this device, like they were doing in December with the SIM-free update. For now, I'll save it for long trips or when I have to use CarPlay apps.
The connection was mostly stable in my case. The only time it disconnected was driving to Big Sur where there was no cellular coverage on my phone or on Tesla itself either, and even so, the car and the device seemed to try their best to restore connection without my help. My biggest problem was that the connection between the car and T2C was too persistent, even after I left the car. Since I didn't put a SIM on it, more than once the car was still connected to the T2C WiFi minutes after I walked away, and somehow it didn't lock, and I couldn't initial lock command from the app. I also got outdated vehicle status (door showed open on rainy days when it was actually closed).
Hope they will continue to improve this device, like they were doing in December with the SIM-free update. For now, I'll save it for long trips or when I have to use CarPlay apps.