The customer service is pretty great. I have access to the GPS. I've been able to get media on and off the phone as necessary. It has unlimited network connectivity and tethering.
I'm not convinced they're any worse than any other carrier.
Most of the asia carriers would compete over their services(no carrier-locked phone). But, in US, it seems like most of the carriers are competing over what phones they can provide.
(People seem to want free phones, and then seem confused when the person that gave you the free phone doesn't want you to use it on the competitor's network. If you buy your own phone, you can use it wherever you want.)
In US, you get free locked phones and you still have to sign the contract.
You see the difference? If you have already signed the contract, why do the carrier still has to lock your phone to its network?
They heavily modify the software running on the phones they sell, and they don't allow any others on their network.