BlackBerry Z10 coming to T-Mobile will also offer LTE connectivity. A test of the network showed speeds as fast as 58.8Mbps down and 25.5Mbps up on a Samsung GALAXY Note II although it should be pointed out that there were no other users sharing the signal. And speaking about the signal, T-Mobile users will have one big advantage over Verizon users. When Big Red customers lose a 4G signal, they are dropped down to 3G. When T-Mobile customers lose the LTE signal, they still receive an HSPA+ 4G connection.
T-Mobile has been able to build out its network using the $1 billion worth of spectrum that AT&T had to turn over after its failed attempt to buy T-Mobile. Additionally, once the reverse merger is completed and MetroPCS and T-Mobile are united, more spectrum will be available to T-Mobile.
source: T-Mobile, LaptopMag via Phonescoop