What a lovely piece! The instrument levels, such as the trombone volume when it first entered, could be a little more balanced. I get the idea this wasn't really "mixed" though.
Like I said, the music in this is just nice! Did you write this?? If so, I have to say 5 stars on the composition! The trombonist was a little outta tune a couple times, but that gives it that raw feeling, and you can't help that a whole lot.
Recording quality aside this is an excellent performance!