This is awesome, but I feel like you're going to struggle to compete if all the content is behind a membership wall.
Totally get the sentiment, but also felt like a membership wall was required for building out a platform that is primarily social in nature. Would be interesting to see what anonymous features we can provide down the road.
If you're going to demand registration, I think you have to make a good value proposition off the bat. Probably in the form of a specific practical way the site can be used as an application, with the social thing as a bonus. Right now it looks like a site that after I spend a lot of time entering my books into for the dubious benefit of seeing a picture of them on a virtual bookshelf, will be a ghost town abandoned within a year.
Maybe make the database tools very general and flexible, with easy exports and reports, and push that first? I think of Goodreads, Librarything, and for a slightly leftfield comparison Boardgamegeek, as database-first sites that build community on the fact that they provide free, specialized, and sometimes publicly accessible databases to hobbyists.