I like the choice of the trombone carrying the melody in this arrangement, but the choice of register is puzzling - many octave leaps that are not in the original Alto aria. An elementary trombonist found it easier to follow the original Alto line.
Thoughts from the arranger:
The piece is meant to be fluid in the trombone part - as the trombone plays both the melody, counter part and other places the bass part. That was the whole idea behind this arrangement.