I am currently taking Adderall XR, 20 mg a day. The stuff is great, but it does take a while to build up in your system so thatyou derive the full benefits.
Plus, you really need to be under a Dr.'s care when coming off of it. Some symptoms of "withdrawal" are depression, anxiety, tremors etc.
Unless you are 2 or more weeks out from your finals, don't take it. I am a big man, 5'10" 300 lbs, and it gave me the shakes for about a week. Now I am settled down, can concentrate, and feel great. I can concentrate, stay focused and maintain a straight line of thought in my head.
Do not get this from anyone other than a Dr. In order for me to go on it I had to take a physical that involved a liver function and metabolism test. I also have to watch my caffine intake. Too much caffine with this in my system can cause some serious side effects (think heart attack). Plus I would be jumpy as hell.
This is not a drug you want to use just to "get through" something. It is a maintenance drug, needs to be in your system for a while and when you come down off of it, you need to be watched closely. Last time I came down off of it, I get really depressed and damn near committed suicide.