i have dat professor, its not bad, but its really annoying when you take a test and have to stare at the answer key for a few minutes only to realize that you are right and the answer key is wrong. this happened to me atleast twice on one of the pat tests. it basically gives you a couple more tests to practice on, with limited explanations for questions. in my opinion its nice but definitely not worth what theyre asking. the kaplan book comes with almost as many questions, plus a whole study book, for only a little more money, plus you can trust their answers to be correct.