I don't know from personal experience additional issues.
I do know the LTE versions don't work with ìApple phones on TMobile. There is a possible fix to make it work, but by default the watch LTE version can't connect to the mobile network.
The fix / work around is to connect the watch to the Apple network using a Samsung /band-aid phone. This pho,.ne must be using the SIM card the Apple phone. Once connected, you move the SIM card back to the Apple phone. The LTE watch will be able to make and receive phone calls plus do SMS / MMS stuff.