Also includes RealAudio clips of authors and author information on the internet. A five star site for people you are interested in books. Provides a list of hundreds of new books by subject each month along with short reviews. An excellent site to find out what's new in your favorite subject. I haven't compared the two on how many hits I've received, but they both seem comparable.
Prices seem to be the same.
I have found that they find books quickly, but expect to pay a fair sum for the service. Most of the other OP sites have you buy the books from the dealer, this site you buy the books directly from Alibris. This probably would make it easier if you planned to buy more than one book. Site looks good. Prices are extremely reasonable.