I love Ellen Hopkins and I have read all of her books! This one is a great companion book to Impulse. You could read either book first and still get the whole story of what is going on. (Impulse is obviously the first one most people read). I found myself really getting into the book as I waited to see where events from Impulse match up in this book and I wasn't disappointed! I don't want to give any spoilers but in true fashion the last few pages of the book not only gives you a since of closure to the various characters in Perfect but also Impulse to the point that you feel for these characters.
If you have never heard of her books or read them they are written in verse but as you read it the verse gives more of the meaning behind the story. There are some you can also read vertically to sum up how the characters are feeling and how they are spaces can tell you what words are heavily emphasize. You would be surprised the reviews I have seen complaining about the book being "poetry". To me it is more like the lyrics of a song than actual poetry...minus the choruses of course.