I used Clear, and found it to be a very, very positive experience.
There were definitely kinks though, most of them came from the IT guys having their heads up their butts iMHO, who routes traffic in the bay area through virginia or washington or whatever?! Come on! Idiots -_-
VZW's policies and pricing suck, and they might very well lose out in aircards, where sprint+clear are doing a great job right now.