I'm prescribed ritalin, and the best way I can describe it is that it makes me not get bored while doing something. It doesn't make me feel "focused", but I also don't feel the urge to do anything else. The main downside with it is that you still have to choose to pay attention to the correct thing, otherwise you can get less work done because you ended up spending 2 hours reading about Godzilla instead of doing what you were supposed to.

I haven't found it to be physically addictive, and don't experience any crash or withdrawal if there's a gap when getting my prescription filled. I think it can be mentally addictive though, because once I became able to study and communicate the same way my peers do, I definitely miss the benefits when I don't have it.