I bought TBR and worked through the problems, but didn't find them all that helpful to be honest. Too many of the questions seemed to be a contrived difficulty, which got to be pretty maddening. I remember reading somewhere on here that EK was the go-to Bio book, and I decided to stick with that. I read it three times and felt prepared during test day. In fact, funny story -- there was an odd bit of bio trivia they threw in the EK book about three times in seemingly random sections. After reading it for about the 7th time, I remember wondering why they kept going out of their way to mention it. Naturally, that exact bit of trivia was a discrete on my MCAT. I would've been suckered into a trap answer had it not been for the EK book. YMMV, of course.
As a side note, I also felt it to be very beneficial to read through actual journal articles. The rationale being that, based upon feedback from recent test takers (as well as my own experience), the MCAT BS is trending towards more in-depth experimental passages that require comprehension of dense, unclear passages and interpretation of data. IMO, there isn't much better way to prepare for this than sifting through the dense, unclear material that comprises your typical journal article. Look up acronyms and words you've never seen before. Try to understand the author's methods, and try to interpret the results for yourself -- especially any graphs. Yeah, it's hard and time-consuming (think hours), but, for me at least, it was time well spent and paid dividends in the end.
This made me chuckle. Thanks 
