I know someone who has this phone, and qualified for it by being, essentially, poor. They get a certain number of minutes each month (100 something), which roll over I believe. If you need any more time, you have to purchase prepaid minutes, not sure about the rate. I think Tracfone probably makes money on this deal, because most people would fly through those 100 some odd minutes in a week. Its a way of getting these phones in the hands of (probably) irresponsible people who don’t budget their money right in the first place.
The minutes technically don't roll over, you have to use them within a 90-day period, although if you keeping buying cards, the minutes don't expire for a while.