Sorry about the Curves reference...
On the circuit training, itself. That style has a benefit of getting your heart going fast and furious, while working your muscle. It can work well for people who are new to lifting and/or exercise, too.
It's often used as an easy to use, starter program at many gyms. My gym, 24 Hour Fitness, has a "Express Zone" area for this purpose. They are non-intimidating exercise machines. They keep your heart going, because you rest each muscle group as you move to the next machine, yet, you don't actually rest...
However, if you're doing it right, you will outgrow this routine quickly. Your muscles will adapt. And, since you give the muscle groups something like 10 minutes between repeat exercises, it's not optimum for working the muscles, either.
Typically, the goal of a good "fatloss routine" is to build or retain muscle mass, create an "afterburn" that will continue to maintain a high metabolism for hours or days post-workout, and burn calories. In that order. After all that, you eat fewer calories than your body needs to support "all that."
Checkout this thread, here:
http://forums.jpfitness.com/showflat...e/0#Post167499
It illustrates the many, many different ways to burn fat. Here's my favorite, from Milko, the "World's Leanest Man": "Diet, diet, diet, heavy weights, heavy weights, ... HIIT " Why? It shows how simple it is, though not easy.
A caloric deficit eats away the fat. While you're doing that, you need to stimulate the muscles so they don't go away with the fat. Get the caloric deficit however you want: eat less, workout more, generate an "afterburn," boost your metabolism by eating high protein or drinking ice-water... The list goes on.
There are so many ways to skin a cat, and we're all demonstrating different ways here. PETA would be horrified.