You mean the Turn It Up, Lay It Down series? I have several of them and they're a great, really simple tool to use. All of the CD's are mixed very well. I first used Vol. 1 when I was just starting out and it really improved my groove. I'm currently working through Vol. 4, which is the swing volume. Each track on that one is just a little bit faster, and it's really helped me improve my swing speed. And it also has trading four sections in every song.
Definitely worth it. Great for improving your groove, speed and sense of time.