Since I'm in an SMP I've read all of BRS physiology. Two things I want to say.
The first is that BRS physiology is more helpful as a review book and NOT to initially learn the material. It's an easy read, and the information is easy-ish to understand, but it won't stick without more context or MCAT-style practice questions.
The second is that you should try to stick to MCAT books to study for the MCAT, that way you don't waste time on material that's not high yield (which will be a lot of the BRS book) and you get exposed to MCAT-style questions and passages along the way. If you really want more detail, try the TBR physiology book.
Anatomy isn't important for the MCAT like physiology is.