I thought that the evolution, ecology, animal behavior, and genetics chapters were excellent in the fourth edition. Other than the A&P chapter, I personally did not like the cellular respiration, photosynthesis, and plant chapter. Likewise, there was little to no taxonomy covered in the fourth edition (which appeared in at least 3 of my questions on my actual DAT).
If you want a different perspective, try Barron's AP biology, which compliments Cliff's very well. 🙂