I used Jillian Michaels - 30 Day Shred [DVD]  to get in shape before my wedding in August, supplemented with The Tracy Anderson Method - Mat Workout [DVD]  and had so many compliments from people - and not just on the day, obviously people say nice things on your wedding day! I recommended 30 Day Shred to loads of my friends because it is less than 30 minutes and still a tough, effective workout. If you're new to Jillian, you may want to start there first.
For me, No More Trouble Zones is a step up from 30 Day Shred. The intensity doesn't stay up the whole time, but I was sweating bucketloads by the end. It's a longer workout, at around 50 minutes, but it's broken down into seven 6-minute circuits so I just focus on that and know each little bit will be over soon! ;-) Each section focuses on different 'trouble zones' - which includes, I think, every major muscle in the whole body, so that sounds about right! There are a huge variety of exercises, which keeps it pacey (look on amazon.com for a great review that breaks down the whole DVD).
Even though I have always found weight training to be one of my least favourite parts of working out (I'm usually a cardio dance/pilates/ballet workout kind of girl), I am totally on board with Jillian on this one. I don't find her arrogant or annoying. Actually I think she's very motivating and inspiring...except for when she very strangely starts advertising a toothbrush on the 'Bonus' section - at least she doesn't start brushing her teeth in the middle of the workout!
Anyway, I'm pretty fit and didn't find this to be a killer but it was a great all over workout that made every muscle feel worked out. I couldn't do every exercise off the bat (like the 'windscreen wiper', eugh, I blame heavy legs!) but I like having something to work at. I have plenty of easier DVDs I can jump straight into - challenge is good! I particularly liked the mat section at the end for the lower body because it had some similarities to Tracy Anderson's style of achieving lean, toned, dancery legs.
Jillian recommends doing her workouts at least 5 days a week, and if you did, I think you'd see great results. I like variety in my workouts, though, as my knees are prone to aching from overtraining in the same exercises (this happened in week 3 or 4 of the 30 Day Shred) so I won't do it two days in a row. It will definitely go into my weekly rotation of DVDs. I also have its companion DVD Jillian Michaels: Banish Fat, Boost Metabolism [DVD], which I think is meant to be more cardio-oriented, but I haven't tried it yet. In summary, however, I really recommend this DVD, particularly if you are not an absolute beginner, and you want a fresh challenge.
If you are a seasoned DVD exerciser, search 'Jillian Michaels rotation' to see how other people put together monthly rotations of her DVDs.