I bought this book with high hopes after reading all the reviews. There were plenty of errors (especially with regards to the answer key...be aware) but mostly I found that the score I was getting in these tests was way off from the scores I was getting from the AAMC practice tests. These tests are good practice for timing and structure, but the answers they provide are purposefully tricky and often misleading...even more so than the actual MCAT....which is saying something. I think it is useful, but only in addition to the practice tests provided by the AAMC.