First things first. Adderall is a form of Meth. Treat it with kid's gloves.
From my limited experience with people close to me who take it, things can go two ways.
When taking properly, using recommended low doses (or even less), it seems that it can really help some people. I have a friend who takes it and it seems to do wonders. He won't take it on the weekends because he absolutely doesn't want to become reliant on it. But he says it definitely really helps him stay focused at work.
However, I have a cousin where it's taken control of her life. She's treating like a recreational drug. She always runs out because she's taking too much, so she begs from her friends. She'll mix with alcohol to get really fucked up. If she goes without, for like a day or so, it fucks her up. She's practically bedridden and feels like shit.
She's wasting away because she has no appetite. Basically, she looks like a Meth addict. Because she is one. She won't listen to us about it. She claims she needs because work is so busy and stressful. Yet she was able to do her job before.
She actually had a seizure recently on a late Saturday night and had to be taken to the ER. She neglected to tell them that she had taken 4 pills and was drinking most of the day. So they couldn't figure out what exactly caused it, except for being malnourished and dehydrated.
Hoping it scares some sense into her, but I'm not holding my breath.