I was prescribed with Strattera as a high schooler, and have used Adderall as well as Vyvanse for studying purposes in college. And while it's been a while since I experienced the effects of Strattera, here's what I remember.
Strattera is a non-stimulant. It is NOT an amphetamine. It does NOT send your heart-rate up, and because of this, it doesn't give you as much of the alertness that stimulants, like Addy and Vyvanse do. It also needs time to accumulate in your body before it really begins to affect you, which I found can be worked around by taking large doses (I would double down on my 45mg if I missed a week as I was bad at keeping a schedule for my pill). I took it for about nine months in school because of my inattentive and disruptive behavior (caused by border-line ADHD). It fixed those problems. It made it easier for me to sit still and decide when it was time to goof around and when it was time to focus on the teacher.
After six-ish months, I began to notice there were psychologically negative effects. While I didn't feel depressed or moody, I also didn't feel like myself. I wasn't as fun-loving and carefree as I had normally been. I felt, essentially, like I was becoming a zombie with a much lower emotional range than I'd once had. After a couple more months of dealing with it, I stopped taking the pill, unbeknownst to my parents, and after a month, told my mom everything about my experience and we decided I no longer needed medication.
Strattera acted as a liaison between me and "being a well-behaved kid" in school. I understood how I acted under its effects and was able to replicate the results off med, and suppress my mental urges to burst out in class or become distracted by minor things.
This being said:
I Do not recommend Strattera as a focus improvement drug for short-term use
Because of the relatively high doses required to yield an immediate effect, it's not at all good for your liver. In my experience, it doesn't increase your cognition and mental acuity the way stimulants do, rather it simply keeps you from being distracted. It's like putting up gutter guards on a bowling alley, where Addy or Vyvanse would be putting the bowling ball into a cannon. You won't fall off track with Strattera the way you can with stimulants, but as long as you can aim your cannon (mind) properly, you'll find much better results.