i've taken hydroxy cut before, and paired with a healthy diet, and good exercise, it can be a very useful supplement.
Each dose contains as much caffeine as you would find in two cups of coffee, so you will be VERY hyper, or energetic.
It makes you not really want to eat, so when you DO eat, you dont pig out, because you'll make yourself sick if you eat more than what you need.
as far as burning more calories, i guess so, because of the increases energy.
taken by themselves, i would have to say no, they dont work, but if you exercise and eat right while taking them, they can show you faster results.