That person is now a different person than before. Some good things, some bad. I want to stress that my family member is very accomplished and has now started to medicate (under MD supervision), after completing a PhD in STEM from a top 25 school with many honors.
The good things are that they are calmer and easier to talk to. They report that they feel more 'together'. They don't freak out at all the little things as much now. They seem to float along now, their eyes are less darty.
The bad things are that they act like a crackhead. I know that's glib, but it's the best analogy I have right now. Appointments and deadlines are flying past like never before. They seem to really not care about the rest of the family as much as before. They are now doing a lot of very colorful art projects in areas that don't really take them (during weddings, on their work desk, on the ceiling of their bedroom, etc). They interject themselves and their feelings into conversations that are not about them (talking about an elderly family member's time left, they make the conversation about them now). Their spouse is very concerned and has expressed this to the rest of the family. They get very angry when talk of becoming unmedicated is brought up. I fear they are addicted to the amphetamines.
My advice would be to go to a good MD and talk with them. Try out the medication for a certain amount of time (~3 months) and then go back off the medication for the twice the amount of time (~6 months). Do an in-depth analysis about the effects it's had on you and determine if the benefits are worth whatever costs you see. Involve close friends and family in this process. Be very blunt with yourself. You've managed to have an effective life thus far, I would be very careful about gambling that.