My ex was addicted to speed and G for a long time. He quit when we started dating but three weeks before we broke up, he had been using again behind my back. I can't describe to you the fucking trauma and pain he put me through during that time. He acted like a fucking psycho and was so paranoid, he'd accuse me of doing all kinds of things I would never do, and also thought people were out to get him - every time he came home, he'd stand at the door with a weapon for an hour before I finally convinced him to come lay with me. He started hanging out with sketchy gangsters, blah blah.
Anyways, it was really difficult for him to kick, and he's still struggling with it. I don't think he'll ever kick it. I don't know how much speed he does, but I know he takes a shot of g every 1-2 hours. The worst was when he'd 'accidently' take too much and g-hole while we were in public. Fucking embarrasing.
I'll agree that it sounds awesome, but man, don't let it get out of control, because it tortures the people around you.