I've taken several, re-watched them on occasion, and feel they were worth the money. I also signed up for a couple that weren't what I expected and got my money back, quickly with no questions asked. You can't really go wrong.
When I am considering a Craftsy class, I always check to see if the instructor has already covered the material in a book. For many techniques, I prefer having a book to a video, since I can quickly look through a book to find just the thing I want, and it's harder to find that in a video. But there are some things in quilting that are better shown in videos, so there's a trade-off.