Taking it recreationally has some merit to it. The euphoria is much weaker compared to methyl. However, a general strong and pleasant feeling of well-being is achieved (at least mentally). The physical side effects are quite taxing though, much more prominent than at recreational doses of methyl.
Come down is not too unpleasant. There is an urge to redose after the peak but it's far less strong than with methyl (still not too weak, though)
I cannot comment on its effect as a study aid. However, I didn't find methyl very helpful with studying either.
I cannot be certain but I'd say it's rather ineffective as a replacement drug for ADHD. Judging from the side effects and the pleasant effects in recreational doses, I'd say that it's much less effective and unpleasant than rit.