As long as you stay under the 5gb monthly cap, you should be fine.
Even if you go over, you probably will still be ok, as long as you don't go nuts.
Awhile ago, there were threads going around on other sites about some customers that were getting warning letters from Sprint regarding excess data usage.
The letters said that if the excess usage didn't stop, service would be terminated.
These threads may have been purposely started by Sprint employees for all anyone knew.
Bottomline is that if you don't get greedy, you should be ok.
I gotta go, I hear a knock on the door....