Wow, now THAT is quality work! I can't get enough of this piece.
I used to hang out these forums a few years ago and got sort of... bored...but your piece itself is going to be responsible for keeping me around for a while longer.
So many things to say, but I really thought your glissandos were very effective, and you either have a very good understanding of the instrument or else you had a very good viola player to work with while writing this piece.
I read in an earlier post that you only had a very short time to write this...sometimes that is when we write out best works. Back in college, the large ensemble pieces I had performed were the pieces I wrote in only a few days. The smaller pieces I took a lot of time on never made it beyond the professor's desk...Weird how that works.
I also want to piggyback on something Nightscape said about the continuity in your sonorities. So often people think that "modern" or "atonal" music is simply random notes in effort to avoid a tonic, but that isn't really what atonal music is and your piece demonstrates that. Or did you just get lucky and we are digging into this piece way too deeply?