I've been a member of Jamplay for almost a month now. So far I've been quite impressed with the vastness of this guitar learning site. There's so many videos and tutorials on this site that it'll take you months to go through it all! They also add new lessons pretty much every day. Personally, I really like it. I read a pretty thorough review on http://www.onlineguitarcourses.com/reviews/jamplay-review.html that talks about it in greater detail.
If you are still a dial-up user though, I probably wouldn't buy Jamplay. You can view the videos in different resolutions, but you'll still spend too much time waiting for the videos to load.
All the best!