Stimulant? Not realy. It helps you stay awake and be more on the ball but I would not classify it as a "classic" stimulant. You will be depressed if you think its going to give you a kick like ECA or Adderall. However, I take a provigil, a nuerogenex, and redbull at 4:30 in the morning and go back to bed. 45 minutes later I am awake, happy, and ready to start the day. Ever see a fabric softner commercial where people wake up happy and make their beds? That's me!
One other thing to point out that I find interesting is that it has helped me loose weight indirectly, prevents some of the depression from the winter blues, and I can talk a better game of bullshit.
Oh yeah, dont take it every day if you dont have to. Your body gets used to it.