Very good. If you like stories about teenagers who feel like they don't fit in anywhere, this is right up your alley.
There's a lot of interesting stuff packed into this short book, and talking about it gives away too many good details, but I will say that from my experience it's a very insightful exploration of the ways teenagers (esp. popular teenagers) deal with the death of a classmate.
I agree with Mare that the cover really does the book a disservice. It doesn't give any indication of how good the artwork inside the book is, or what the story is about. Do you hear me, publisher? We reject this cover, as the authors undoubtedly did.