Ally - the Biggest Loser ones are fairly full on.. having said that, they have great warm up and cool down sections, and they have a few different workouts to choose from. you can even mix and match and do a couple in a row when you get really fit! me - i can get through half of the high intensity work out, then I die.. its full on!! the low intensity one is alright though., and when you get stuck, start walking!
One of the best things about it is the stories from the contestants, you see the before and after photos and hear someone talk about their journey, I like watching it before because it really motivates you to lose weight.
I'd recommend it, maybe when you get sick of your current dvds, give it a go!