I can't recommend it enough - I think it's a fantastic option. I can speak mostly to the quantitative program, because I didn't study for the verbal. I was starting basically from scratch, as I've been out of school for an awfully long time and I didn't get much math there anyway.
I followed the curriculum in the recommended order, and used the "Learning Guide" to structure my studies. Basically, it recommends what videos to watch and in what order, then what OG and OG Supplement questions to do.
The videos are really, really clear and progress nicely from one topic to the next. They don't presuppose a lot of prior knowledge, but at the same you do need to go in with some basics (as in, can you do long division, etc. . . just the core stuff).
I started on my first practice GMAT with a low quant. score, and ended up with a 47 on the real thing. For a liberal arts guy, it was a big progression. The course is really great value (also, there's a good number of sample free videos, so check those out).
Let me know if you've got any more questions about it - happy to answer those that I can.
