I have used this for over 3 years, nearly every day. It is by far my favorite energy drink. You feel great when you drink it and don't get an energy crash later on. I find that it works really well for about 5-6 hours. The flavors are great- I recommend fruit punch, strawberry mango, and watermelon. I always recommend it. A small tip is to mix it with room temp water, and add ice after to make it more enjoyable!