Gilad’s Origami Page reviews over 175 origami books. His reviews include the difficulty of the models and the clarity of the diagrams. A great place to check it out!
The Origami Database contains over 2000 book titles. The books are listed alphabetically and are briefly described. Some books have accompanying photos and some have reviews. Maintaining the database is an ongoing project and some sections are incomplete. Searches may be slow to load due to the extensive size of the database.
Amazon.com has over 5000 books listed for sale. This online book store has editorial reviews and customer reviews. Books are ranked on a five star system. Sometimes a used copy may be available at a reduced price. A great place to browse!