Well I have to cram for my AP Biology exam. The thing is that I have barely touched the actual Biology textbook, and I only have < 2 months to study.
So my question is should I study my Cliffs AP Biology Review book or my Biology Textbook?
In my opinion, Cliffs gives a very in depth review of everything that is AP Bio, but it goes WAY in depth compared to other prep books, so it’s kinda overkill. I used it last year and, well, I didn’t do as well as I wanted to on the AP test, but some people used it and did very well. Experiences differ I guess. 
As for your textbook, I’m not sure what textbook you use, so I can’t help you there. If you’d like, get Barron’s. I used it for my SAT subject test in bio and got a 750, so I’m assuming it’s good enough for the AP test as well.
You have two months, which is a good amount of time to study for the test (considering if you don’t take 7 other APs). Cliffs is good for review, and I’m sure your book is good as well, but for Cliffs, I doubt you’re gonna need to use all that info they give you for the AP test.
Thanks for the advice, studying for it now!