I tried it once a while ago. I lost fat while on it, but I think it was the diet and cardio. I didn't feel any effects of most thermos. I sincerely doubt I'll ever use it again.
It is one of the few that I do like. No after effects and you dont need to take a huge amount everyday. I like to rotate my fat burners so Im not consuming the same thing all the time. Plus it all comes down to your diet in the end. You can take them but diet is what really changes your body.