Based upon past experience working with Sprint in the WAN arena, Sprint = Epic Phail.
I mean, c'mon, the US hasn't even gotten up to speed with HSDPA like Europe/Asia has, with only one carrier (AT&T) having it right now in "selected" markets (read: about 17 cities/metros with populations of 1 million or more).
Then you have Qualcomm pulling stupid stunts [url=http://thejournal.com/articles/20419]like this[/i] instead of really pushing for true GSM 3G or WiMax across the board with all carriers.
I would expect WiMax to be more heavily rolled out in Europe and Asia before it even comes close to being real-world usable in the US.
I lived overseas for more than 13 years and even when staring at a herd of camels on the border of Iraq and Kuwait I had full 3g HSDPA access!
Then I come home to a wirelessly-crippled country. Ugh.