Exactly. There might be room for this site, just as there's room for Digg, Reddit, and plenty of other social news aggregators, but this appears to be in no way ground breaking. It barely enhances one's ability to use, learn from, and enjoy books, in basically the same way as several other sites with similar functionality (LibraryThing, Shelfari, Goodreads, etc.).
I am not familiar with GoodReads. I posted this mainly because there was a discussion about having an HN bookclub here recently, which (predictably) quickly forked into a discussion about a bookclub start-up. To my knowledge none existed but I have noticed at least three now including the one you just mentioned.