The main active ingredients in JTM are taurine, an amino acid, and glucuronolactone, a carbohydrate derived from glucose. Along with those two powerhouses, you'll also find caffeine, which definitely adds a boost.
JTM recommends cutting the drink with water, and I find that about half water, half JTM ratio works fine.
This drink definitely gets you going, and it works well to give you sustained power on long rides, runs, skates, or skis -- whenever you're exerting a lot of energy and need a boost to keep going. It'll also get you going before you step outside the door, however, so be careful.