Describing the feeling i think is counterproductive because everyone has a different experience from medication. I think the best advice is finding the point where the positive effects are worth any negative side effects. Thats why i am a big believer in a slow and steady approach to adjusting meds. For me i like to really understand what is happening to my body and brain before i move on to the next dose / medication. I kept a daily journal at each change for a couple of weeks of how i felt and how it changes the ADHD symptoms plus any side effects and shared that info with my DR.
That let me draw on his experience and helps me remember what it was like before . I think i am quite lucky with my Doc because he takes every bit of information i provide into account regardless of how small and insignificant i think it might be.
The thing to remember is that its your brain you are playing with and its a complex machine so small adjustments can make a significant change. And i have found that the better my ADHD symptoms get the more aware i have become of the effects of meds because my brain now has more spare processing power to think about it all.
That instant improvement that heaps of people feel when they start meds and the worry they feel when those effects seem to fade starting doses seems to be common from what i have read around here. But for 80 percent of people with ADHD stimulant meds will provide a good outcome. My biggest worry through the whole process was the worry i had when the Dr picked up that my blood pressure was getting a bit high with Vyvance and I thought that this little gift might be taken away from me. But we found a way to deal with it and as i said now i think i have found where i think i should be in relation to medication and dose.
In short its a process that takes time and the key to it all is be honest with yourself and your Doc whilst working through it all and invest the time to find the best option for yourself.