Not really Colloquial,
This review is from: Colloquial Spanish 2: The Next Step in Language Learning (Colloquial Series) (Paperback)
I'm really disappointed with this book: it doesn't neither teach you any grammar (it does actually try to teach you something in a very mixed way) nor help you learning familiar/slang expressions. It's just a sries of very short discussions.
The words presented in each chapter are very few and not really "colloquial" ones. I would rather suggest people to get the combo A Modern Spanish Grammar plus Spanish Among Amigos.