I am a new t-mobile customer coming over from Verizon. I have to say in my area it has been very solid. I have zero complaints so far.
Speeds on my Note 2 are the same as Verizon at my house. Speeds around town are a little slower but not much. In a strong signal area I see 12 to 19 down and 1 to 3 up. That is right on par with Verizon