To be fair, I haven't thoroughly used this product. I got it through the EmpowerGMAT deal. With only one month to the exam I didn't have much time to use it. I didn't get the score I wanted and so I'm writing this review to gain two weeks of access.
I did do a few quizzes and I really liked it. The questions are well written, the explanation's are awesome and I really like the fact that software looks like the one of the official GMAT. I think this helps because when I have used other courses to practice their questions work slightly different which can be annoying.