if you're getting 34+ on average, give it a whirl; I used it and found it very helpful at honing my skills with trick questions and those that require test-taking skills to get out of. if you're in the 30 range, give it a try if you'd like, but there are other tings that will certainly help your score (and not hurt your pocketbook) more than this book.
that said, be careful- it is what it says it is. that is, if you invest the 25 bucks, get ready for a book of brutal questions that will make you question your intelligence. if you can keep that in mind, then go for it.
I used the Kap 45 book over the spring break and it might be the only prep I would have.
It was a brutal book and, sometimes, after reading a passage you barely get a good idea of what's about. I took the tests under timed conditions, and usually got about 60-65% of the science questions right and 72% in the VR portion. I really don't know what this means as regards the real deal coming in April. But as I said before, I am praying for the Mercies of Providence as I abhor the nature of this inevitable exam.
Also the Kap book did a good deal of work in reinforcing/refreshing science concepts.