If you are serious, buy it. I use it all the time to refresh and prep for entrance tests. These are the people that write the tests you are going to take, and this is how they think. Get in their heads and get things done. I love that it gives you the exact page the answer is on, so you can also look it up for yourself and understand it better. Also like that you can add to your study deck to review later. 4/5 because some answers are too easy, and sometimes it crashes when I go to another app.