Tried this. My experience: Free, great data, HORRENDOUS voice. Voice is unusable and even worse - unreliable. Sometimes your call just does not go through / you just don't get the incomming call. Works on the Sprint network. You can get a Samsung Galaxy 3 (Sprint) for under $100 on ebay. If you need a phone for data and unreliable voice for free - this is your service. !!
I've tried FreedomPop in the past, and people were ranting and raving just as much as they are now, and it couldn't have been more of a scam.
I got a wireless Hotspot through an online promotion, and not only did the wireless Hotspot fail to work since day one, but to change or cancel your subscription plan, you actually have to call in and talk to a representative, which for me, included sitting for over 4 hours on hold. For what was supposed to be a $40 hotspot and free wireless broadband, I ended up sinking another $30-something dollars under false-pretenses.
ie. Be wary of this company and read the fine-print.
Sucks from the comments I'm reading.. if they tightened their belt and made the service some non-aol legit service (were cancelling wasn't a 2 hour high pressure ordeal) especially with modern times; the reputation (good or bad) spreads like wildfire. So these guys sound to be shooting themselves in the foot. Sad because it looks like an excellent idea; atleast as a suppliment to current carrier contracts; can't say I'd be ditching my current plan for something like this without some good history; and with high pressure (pain to cancel) I'll probably be avoiding it all together until they get their ducks in a line.