I've had a few occasions to deal with them. The nice part is you get a working phone very quickly. And they honor your original warranty with the refurb. If you live close enough to an AT&T service center, you can just walk in and swap it.

The only catch is you have to give them a credit card number in case you don't send the original phone back, but they do even send you a pre-paid shipping label, so there's no money out of pocket.

 

The ones I've been sent (three in total but only one of them was a smartphone) have been in virtually new condition. They were clean, scratch-free and completely stock. In each case they sent only the phone body (and in the case of a Samsung Eternity that lost the ability to vibrate) they didn't even send a new back cover.

If I recall, you have 10 days for them to get the replacement before they charge your card, but I may be wrong on that point.