How do you define legit? How does ibookdb generate income? Are you a book review service? Do you charge for book reviews?
I presume ibookdb means legit as in they are not crooks. But I think there's a separate question of whether they are comprehensive, meaning do they have at least basic info on just about ever book currently or recently in print? I doubt any site is comprehensive by that definition except Amazon.com, and for Amazon it's only secondary and accidentally, as their main purpose is to SELL books, not make book info available to anyone who looks for it. I do rely on Amazon for a lot of stuff not book-buying-related, such as looking for other books by an author, looking up the publisher of a certain title/edition, and of course reading reviews (which are sometimes good entertainment in themselves).
Here's Wikipedia's article on book-related databases, which gives some info on ibookdb:
http://en.wikipedia.org/wiki/Online_general-interest_book_database
About ibookdb: "It was started as an effort to be the
IMDb equivalent for books. It currently contains information on over 77,000 books (over 237,000 ISBNs), 21,000 authors and 2,100 series making it one of the largest online databases of author and book information."
Hmm, not sure what numbers would be truly "comprehensive" but that's better than I suspected.
"Registered users can catalog and manage their book collections online,..." Oh, just like LibraryThing.com.
As far as reviews (and this may have no connection with what any book database is doing), I recall a Usenet newsgroup where movie (and book?) reviews were posted, apparently written by professional (or wanna-be pro) reviewers, each one with a strongly worded copyright message. It appeared the idea was for the reviewer to put it out there for newspaper and magazine editors to see, and buy print rights so they could easily add content to their publications.