I am a high schooler and I play trumpet. My best friend, who plays oboe, wanted to play this piece for our solo and ensemble contest, so we bought it.
It is a really beautiful piece of music... the trumpet part has some hard spots, like fast repeated notes and...
two really exposed cadenza-type sections, but overall isn't bad. My friend learned English horn for this and she says the only hard part for her is the really high notes (such as E above the staff).
Our pianist, who is also in high school, says that the piano part isn't too hard for him. I don't play piano, so I'm not sure what the difficulty level is. Overall, I'd say it's at a late intermediate level, but you can play it and sound like a pro!