I started my prep as a self-study. I choose Magoosh because of it's accessibility in price. I didn't want to shell out a massive amount of money for my course, and in that sense, Magoosh definitely met my needs, because I find it's one of the best value preps out there. I used Magoosh in the following capacities:
1) I was a strong Verbal student, so I went through maybe 25% of the verbal questions, and did not review all of Verbal videos, though they offer many. I did review the Sentence Correction Verbal videos, however, because that was an area of weakness for me. I found that reviewing those videos, paired with an intense study of the Verbal questions (Very Hard Questions) led to the strong score I received in Verbal.
2) I used it for Math review. I watched every single Magoosh math video, and did the questions related to it (From Easy --> Very Hard). At the time of my exam, I was getting every "Hard" question right.
Overall, I scored a 700, with a very high V score, and a low Q score. That leads me to believe that even though I devoted 80% of my time to Math, I wasn't able to reap the rewards I wanted. It's for this reason that, while I think Magoosh prepped me well, I encourage low quant people to look at courses aimed at improving Quant scores.