Just last week, Sprint finally lit up its LTE network. Not before selling a number of LTE-equipped phones, however. If you were worried about Sprint's ability to keep up with the big dogs in the race to expand LTE coverage, the WSJ has some comforting words for you. Wait, did I say "comforting"? I'm sorry, I meant worrying. Very, very worrying.
The long and short of it is, Sprint simply doesn't seem to have enough spectrum to keep up.