At first I was really sceptical about GFuel but after seeing it beeing on the scene for quite a few years i decided to give it a try. And after trying it, it exceeded all of my expectations. It keeps me up when i need it, i'm not experiencing any crashes or any side effects and I feel good even after drinking it 2 or 3 times a day. Also i'm not having any problems with falling asleep.
The only bad thing are the shipping costs. They are quite pricy but that might not be the case for all countries.