They are something i have never tried although i have seen them on the net and the TV, i am what you would call old school and use weights for 1 - 2 circuits per week.
I worked in the leisure industry for 10yrs gaining a leaders certificate by BAWLA and i am also a fully qualified swimming teacher (ASA).
Things have changed in the industry since i left in 94 but one things for sure exercise works! Someone recently quoted if one of the pharmacy companies had just brought exercise out as a med it would be the best med with the most benefits to ever be released!
There is another weight bearing exercise called cross fit which looks like a good calorie burner, i liked the YouTube video with the dead lifts at the start. These are my favourite movement ( i use a barbell ) and you can tell they work well when you have an appetite shortly afterwards.
Movements like deadlifts are core movements and they are also compound movements in which major muscle groups are used along with smaller muscle groups. These are the best ones to use in the attack against fat, isolation movements like arm curls are OK if want to just work your biceps or do a little extra on them but overall here compounds are the way to go IMHO : )