I use to drink muscle milk. It didn't seem like it did any thing. You won't lose fat; thats just something they put on the bottle to help market it. Your better off just getting some whey protein for a post-workout shake. I read on a t-nation site that stuff caused nerve damage or something?
tried to once, it was okay, i did notice a little bit more energy when i drank it compared to my usual pb&j for my pre-workout snack. But in my opinion its tooo thick, and not very tasty.