We live in a major metropolitan area so the coverage for us will be fine for how we'll use it, but when we travel we take my regular work cell phone which has full coverage.
For how we'll use the prepaid phone, our bill should be around $5/month instead of the $24/month we're now paying.
Oh yes, with T-mobile, the minutes are good for 1 year (once you have spent $100 in minutes) but they actually last forever since your expiration date changes to the new date whenever you buy more minutes. The phone costs around $40 at Costco and comes with 60 minutes. Buying a thousand minutes for $100 = 10 cents a minute, but the minutes are more expensive if you buy them in smaller increments.
I'm kinda worried about the coverage issue. I'd hate to buy a Tracfone only to find out the phone can't connect when I need it to..