I love Davina's earlier DVD and always feel good (if exhausted) having done it, but the 1 hour thing is a big obstacle for me - it's just toooo easy to say "haven't got the time/energy today" so I rarely use it.
This one has proved mostly ideal - half an hour is long enough to give you a decent workout, and short enough to find yourself doing it easily every day. It doesn't leave me wiped out, like her earlier DVD, so I have energy to go off and do whatever I need to do, or do it before work even. Amazing!
The first section left me unable to walk the next day, in spite of only being half an hour, so you really feel like you're getting fit. The second section felt like I wasn't using any particular muscles and only really getting an aerobic workout, but the next day my arms, shoulders and back ached (in a good way - muscles being worked!). But the third section was the let down for me - a bit of Pilates and Yoga-ish positions, but not as good as the real thing. I still ached the next day, but the workout was too sporadic - a few really full on excercises interspersed with a lot of sligtly limp stuff.
For this kind of core stability workout, I'm going back to the brilliant MTV Pilates, which is also half an hour long (well, 35 mins) and truly does what Davina's Core section didn't do for me. But two out of three ain't bad, and I'll be doing the first two regularly.