I used to take a small (limited to 6) Pilates class 2/wk. We did mostly mat Pilates, but also used the reformer and the cadillac (which struck me deep with fear when I first saw it... it looks like a torture device!). I cannot communicate to you how much it changed my physique.
Things change! The gym was taken over by another company, and the instructors moved. x( Now I'm left to try to find a substitute. I've taken a few classes here and there, but it's hard to find something that compares! ;( So I got some of the Stott Pilates DVDs, because I heard good things about them. I think the basic principles are pretty good, but Moira (the instructor) sends me over the edge. Not exactly something you want when you need to be focusing on your body. Her high-pitched runsallthewordstogetherduringanexercisetoIthinkhelpyouholdaposition - and then the "release" of her voice back into something dogs don't bark at, truly bugs.
All I can say is that Stott seems to have some nicely structured workouts with a variety of levels and equipment usage... so if you can stand Moira, then it might be worth checking out.