Room for improvement...
To maintain a database about media like books seems to be a natural purpose for an app, however my experience is very mixed: I started with iBookshelf, where the scanner is quick but even best sellers are not found in the database - therefore I switched to Book Crawler: the scanner is a joke - even in totally identical situations it would one time work and the other time not, without any apparent reason or message. What is totally confusing: there is not whatsoever sign that the scanner is active. I got used to enter the ISBN via the "Google Books" input option, and this works very well! The overall look and feel is a bit "toyish", but I would it works and the app is overall much better than iBookshelf, also because it works in "landscape". Maybe the developer of Book Crawler can integrate the scanning module used by iBookshelf, than the app could become four stars or better :-)
hawupp about
Book Crawler, v5.2.9