I like the length, but it ended at a point that you could launch a C section or another *mini-movement*. Personally, I think some people are obnoxious expecting their listeners to wade through their compositions. I remember many, many concerts that I wanted to end by intermission because the composing was so obnoxious. Of course a great composer can keep an audiences attention for much longer a period. That's my goal ultimately, but if one feels he can't do it, don't just fill your score with dots for 20 minutes.
I have a recommendation, if you're a professional. Write a solo guitar version of this where the melody is along the top strings(?) There's a good market these days for solo (classical or jazz) guitar works. Those compositions, except with great rarity last only 3-6 minutes.