I've heard different opinions from several people, mostly women, about this thing. Some really like it, while others don't at all. Personally, I wouldn't try it myself. But if you do decide to try it, it's best to start with a small amount to see how your body reacts to it.
I've tried it alone and during tests. I enjoy it a lot, as it keeps my heart rate up all day and I feel less tired while doing cardio.
I think it's a good option if you're into that, but remember, your diet matters most, about 90%.