I've used it once for the Computer Science Course and the course on Formal Logic. I followed the courses fully and, most of the time, the videos are created specifically with the assumption that you'll do the exercises.

The computer science course was entry level fiddling around in a simplified form of javascript (IIRC), but very fantastic. The instructor was clear, concise, engaging, and all around awesome. Near the end of the week he gave a few full hour long lectures from his own class at Stanford and the concepts he was teaching were awesome (Like how sound works on computers.)

I wish I could say the same for the Logic teacher. I quit about 4 weeks in because I couldn't get the material fully soaked in and the teacher's style of lecturing was really not good, imo. He mostly made very short videos and deferred you to the text on the site, which while comprehensive, was a bit too confusing for my taste. I understand having rigor, but I recall rereading it five times and just couldn't parse it. The other students seemed to also voice similar complaints the last time I checked. The reason I took this course was because I went through Hurley's Concise Intro to Logic on my own and did amazingly well on it, and had lots of fun doing so (more fun than any other subject I studied).

Maybe I need to give the Logic course another go, but my time with it wasn't what I imagined it would be...

I was planning on taking a few more courses, and I DO plan on taking that Intro to Guitar Course, so overall I guess I could say it was a positive experience