This was kind of loud overall, but especially for an ambient piece. Instead of setting the mood, it takes over and says "LISTEN TO ME!". There are even parts where I can hear clipping, so I would go back over this and really isolate each voice making sure the loudest one doesn't go over -2dB while keeping the whole thing under 0dB. The ending felt way too abrupt for the pace you set, I'd let that ring out with a longer fade.
What I'd do from here on out is the multi-speaker test. As you master something, listen to it over as many different speakers as possible (headphones/tower/stereo/car) and see what you notice each time. It took me one listen with headphones to realize this was mastered way too hot.
On the plus side, you kept it simple. It was energetic and you used some variations in the form so as not to get stale or boring.