Everyone reacts differently. I know that I had LOTS of energy and was hornier than I have ever been while I was on it...exactly the opposite of what should have happened.
As for HOW it works....dunno. I know I saw big gains in strength but they faded rather quickly. My guess is it doesn't really build mass but more so the nerve to muscle response. And be careful....the muscles might grow quick/get strong easily but the tendons don't keep up. If yer looking into running it for a while look into taking some complementing
AAS which will help build the connecting tissues as well.