I love their wish list feature.The website is easy to use and their filters are effective. They inform you about the conditions of the book. I have ordered more than 10 times and never got a book which is different than the description.
I found thriftbooks some time ago and decided to give it a try. The books are cheap, there's free shipping in the US, there's nothing to lose. I bought two or three books and was completely satisfied with the quality. I've now made around 10 purchases from thriftbooks and have a growing list of 10 more books I plan to buy in the near future from them! Definitely a AAA site to buy books from. I've never had any problems with orders or payment. Very trustworthy site! :)