The one issue with T-Mobile is it uses the fairly nonstandard 1870 MHz frequency. I don't know of any other carrier that does (anywhere). I assume this is because AT&T has the rights to the more common frequencies in the relevant markets? I wonder what technical and regulatory hurdles stand in their way for switching T-Mobile infrastructure to also do the "standard" frequencies.
Wireless really is a mess in the US. Europe and Australia have really benefited from choosing one technology (GSM). In the US you pick your carrier then pick your phone. Elsewhere you basically pick your phone then pick your carrier. Don't like you carrier? Swap your SIM. Problem solved. The US really suffers (from the consumer point of view) by this lack of carrier mobility.
It's my theory that US wireless is so expensive at least in part due to it being the most balkanized market in the developed world (and possibly the entire world).
I was hoping LTE would help alleviate this problem as it seemed to be on the road map for 3 out of 4 of the carriers (all but Sprint). Now I guess it's still 2 of 3. Sprint is still the odd man out with the (basically failed) WiMax technology.
I can see this acquisition facing some serious regulatory and legislative scrutiny.