Prep Expert was effective in raising my SAT score. I scored a 1500 up from 1410 and the main reason I signed up for the class was the guarantees. The guarantees are 100% legit but YOU NEED TO PUT IN THE WORK. They aren't going to give you slack on missing more than one homework assignment because there isn't a reason to give you your money back if you aren't applying yourself. There is absolutely nothing to lose if you do all the work, take the tests, and attend the classes. Either your score will go up or you get your money back. However, the only downside was the essay grading which sometimes took a week after I submitted to get it graded, which didn't help at all because I was not able to track my growth in the essay portion. I even received a couple essays graded after I had taken the SAT like they would benefit me then. They need to hire more essay graders. I also had trouble logging into class occasionally, and if this occurs make sure you contact support and let them know so your guarantee doesn't go away. Overall a great course, Thank You Prep Expert!