Heck of an accomplishment for a 15 year old. After hearing it, that's one of the most impressive young-age-music things I've ever come across.
I do think, though, that it suffers from no flaw of its own (I can find very few in the construction), but from the fact that there are too many concertos like it. It doesn't establish enough of a unique place for itself among concertos. Yet I can't blame it, as it was written by a prolific 15 year old who was no doubt absorbing the compositional trends of his time.