I had a play with it the other day just to see if it did what I wanted. It doesn't.
Adding books to the library takes ages. Multiple file additions aren't possible if you want it done properly.
That said, it's not far off. It needs stripping down to lose the extraneous features and streamlining the features that are there but aren't currently the focus of the application.
Although not free, I think
BookPedia might make a better starting point. I prefer it's familiar iTunes like interface and it has a lot of the features I would want in an application of this type. I'm messing with a demo of it at the minute just to get a feel for it. It has the same limitation of books in that items have to be added individually which is going to be a common theme among existing applications since none of them cater exclusively to ebook management.
More thoughts in a future post.....