Well, I tried T-Mobil for part of a day, and what a let down it was for me, and the area I live in. I experienced either no coverage, Edge most of the time, some 3G and very little 4G. In my home its none to Edge.

Not even one day of use. Went straight back to Verizon. They have a long way to go but wish them luck.
T-Mobil tech rep that handles Apple products tried to fix the issues, but told me finally that I bought a Verizon model, not the T-Mobil version with the 1700 band and that was why I did not get good coverage. Unknown if that was true. Not to up with this stuff other than, it works or it does not.