I own a TracFone and they are as reliable as any other major carrier (see their coverage map). You buy time--minutes to use--and you also buy time--days of service. So, if you use up your minutes before your days of service run out, you buy more minutes. If you have minutes left but the days run out, you don't lose those minutes, they roll over to the new days you buy. They also transfer to a new phone if you decide to upgrade. Go to their website to see what minutes cost for texts and sending photos. It varies by maker of the phone. You can also buy a monthly service or a value plan which I haven't tried. Buy a phone that comes with triple minutes for life and you will have a real savings. You get to transfer your telephone number to this phone or from your cell phone. I bought mine through QVC because they will take it back if you return it within a certain number of days. If you want to read the reviews at QVC, just click on one of the two Tracfones they offer. Read everything on the Tracfone site.
Source: http://www.tracfone.com; QVC.com