First, the positive stuff:
The mastering, I thought, was good for the most part. Nice balance on all the instruments, and no clipping problems I could here. Also, the song flowed nicely from one part to the next, and felt natural as it progressed. Also, you didn't begin or end with drums, which I liked.
Now, I have nothing negative, per se. However, I couldn't exactly tell what you were trying to do with the song. Was it Dance? Was it Trance? Was it both? If you add, say, a high-pitched sliding synth, you'll have an awsome Trance song. Add more prominant drums with a few extra synths, and you have an amazing dance song. As it was, it felt... incomplete.
That being said, it was still a very, very good song, but I would love to see a remake of this in the future.