If you could chop this book up into pieces, the whole first half of it I would give a 1 star rating, the second half I would give a 3.5 star, so I've met in the middle with a 2 stars.
My main problem with this book was the overuse of similes and metaphors, as many people have already mentioned. Mafi says the same thing fifty million different ways to make sure you REALLY get what she's trying to say. Except in the many cases where her similes and metaphors don't even make sense.
My other problem was that I didn't really care for the main characters at all. It isn't until the end of the book when characters like Kenji, Winston, and Castle really get to shine that the book finally starts to feel worthwhile to me.
Overall, I think Mafi tried a little too hard. If someone took scissors to this book and cut out all the extraneous, unnecessary crap, the book probably would have been a million times better.