I loved the Magoosh online GRE preparation. I think it really assisted in my preparation for the exam. As I wasn't one with a schedule that was amenable to the in-person class, using the online methods really helped my score. I was able to study for the GRE whenever I wanted. I also found the practice tests comparable to those given by Kaplan, which is not typical of external sources of practice exams. Their "endless" supply of questions for the exams really helped me study and most definitely caused an increase in my score. I was able to take multiple practice exams leading up to test day and my exam was high enough that I didn't have to retake the test. I also really liked their essay services, which assisted with writing essays. Review collected by and hosted on G2.com.
The only bad thing about the Magoosh GRE preparation is that I found a few of the questions very repetitive. This could be good, as the GRE tends to recycle questions, but I found myself spending extra time during study sessions because I wasn't getting new questions. But, as they say, practice makes perfect. Review collected by and hosted on G2.com.