I liked this book, mostly for the way that being different is portrayed, and as another reviewer said "sympathy for diversity", which is the main theme that drives the book forward. The narrator is refreshingly cynical and has a very discerning outlook on life: she's also very intelligent, so while it's a fairly light read, there's nothing mindless about it.
The issues surrounding OCD are sensitively handled, though towards the end it started to scream a bit of having a "message", which I find off-putting, especially in a book with so much promise.
I just couldn't get away from the one thing about it annoyed the hell out of me - Seamus is far too perfect. The start is authentic and funny, but then he comes along to sweep Grace off her feet and it totally lost me: I found it thoroughly unbelievable and trite.