Its interface is part Tumblr, particularly in two aspects: each user has a blog within the site, and the main dashboard page includes a Tumblr-like feed from other blogs. And it's also part Goodreads, with a visual bookshelf that users can fill with books they've read and add reviews.
I have not had a reason to use Booklikes yet, but LitReactor had this to say when they covered the launch back in May:
The biggest difference between this and the many similar sites out there: BookLikes is geared more toward book blogging and reviews. When you sign up, your Dashboard page features a slew of Tumblr-style posts from various users, who you can decide to follow or hide. I saw a few internet-mandated gifs and pithy blurbs, but this Literary Explorations person offers some astute analysis of book covers and classic reads, so it seems there's some quality there.
I've looked over Booklikes once or twice since it launched and I can see the value in an explicit blog focus - and that goes double after Goodreads latest policy change. Many people are defending the new Goodreads policy against reviewers discussing author behavior by arguing that the topic is beyond the purview of a book review. This is true, but thanks to Booklikes' focus more on blogging and less on book-related reviews it doesn't matter.
On Booklikes a book reviewers is more of a book blogger, and there is very little that is beyond the purview of a blog post. If a member wants to write about a theme that shows up in a half dozen unrelated novels, or point out how a character in author's book is arguably the same character as one in another author's book, they can.
Booklikes is in effect giving reviewers tools that Goodreads reserves for authors (who can start blogs), and that is probably the first and biggest difference between the 2 sites. If you are a reviewer or reader and you value independence and/or not being a second-class member, I think you should look at Booklikes.