I got the Zaggora Hot Pants with a Groupon offer - it was few months ago now, but I think I paid £19 for them.
If you wanna read about all the claims - please, go to their website.
Personally, I didn't experience any increase in helping loosing weight but I admit I haven't been wearing them ALL the time. I wear them during the day, around the house (I work from home so basically a minimum of 5 days per week - 10 hours per day) but I can't wear them when at the gym or at nightime; simply because I get too warm and so uncomfortable. I tried to exercise in them but I had to stop because I was so hot that I felt like fainting.
In my opinion, what all the testimonials on the website are experiencing is water loss (a bit like the foil suits of the eighties) and people that maybe have a lot of weight to loose and they would see a difference even without pants, as soon as they make few changes to their diet.
I did notice an improvement to the appearance of my skin: The skin on my thighs and bottocks is definitely much smoother and softEr and even my fiance' commented on it. :)
Well, in conclusion, I don't really think they are worth all the hype - I got them and I'm wearing them... until one day I'll forget about them and I won't miss them!
Have you tried them?