I've never seen the show The Biggest Loser, so I haven't seen Jillian Michaels in that setting, but over the last couple of years I've tried out several of her workout DVDs. They're very popular: the library I use has quite a few of them; others I've tried through Netflix. And some of them have made their way into my permanent collection. Jillian Michaels' workouts are challenging, fast-paced (in a good way), full of variety, and effective. 6 Week Six-Pack is no exception
6 Week Six-Pack provides two approximately 35-minute workouts. In keeping with the DVD title, there's an emphasis on abs, but the workouts incorporate enough cardio intervals that both workouts are good all-round exercise sessions.
They're a convenient length, filling what I perceive as a gap in the workout DVD world: you can find tons of 10-minute workouts, and plenty in the 45 - 70 minute realm, but the 30-minute workout seems strangely enough to be a rare breed.
Each workout starts with a warm-up. You then go through two circuits of multiple exercises. The second circuit repeats the first (or mostly so) but at a faster pace. The two circuits are followed by a brief cool-down/stretch.
The first workout is a bit easier than the second, but there are modifications provided for making the first workout harder or the second easier. In the second workout, the music gets a bit faster near the end, and Jillian goes into a dramatic you-can-do-it tough-love mode; this can be just the thing to get you through it, or annoying, depending on your mood.
I would definitely recommend this DVD, especially if you're a fan of Jillian's workouts and/or if you're looking for a good half-hour cardio/ab workout.
Other reviews here, here, here, and here, and Jillian Michael's site here.