I gotta say, I'm surprised there are not more postings under this header.
I decided that I really needed to work on my rhythm playing and figured this would be a great place to start. I've raved about other justin products, but I think this may be the best one. Great way to quickly get your head around playing loads of songs, and the chapters on 7th grips and gospel slides are simply outstanding. Has really helped my rhythm playing and am now figuring out all those Steve Cropper/Stax tunes that had previously eluded me.
I think this is really essential learning for people who want to play songs and jam with others.
edit: ignore the above. Still good stuff, but I found all the question threads I was looking for in another section of the forum.