Ive been using them for a few years. Some stuff to note: you have to pay in at least 3 month blocks. You cannot pay for a month at a time. The prices on the website are just for your first term. After that it is a little more expensive, but not too much. Coverage wise it's t-mobile's network, so its good in major cities, but spotty in rural areas.

Ive been mostly pleased with them. When the wife and I go on trips, sometimes my phone gets no service, but she's on AT&T, so her phone usually works fine, and she'll turn on hotspot so i can get my messages.