First of, I apologize for the low score. You wanted a constructive review, however, so I'll try to be as honest as possible.

The biggest issue here, is that the song is atonal. It sounds as though the notes were placed at random in a hopeful attempt to make it all sound harmonic. This is, unfortunately, not the way to go. In fact, it creates a fairly unpleasant listening experience.

Apart from that, the song is fairly repetitive. I can hear you've tried to put some variation in the song, but the small amount of patterns clearly shows that you basically looped things over and over. Again, not the way it should be done.

Mastering/mastering-wise, the song was okay. There was no noticeable clipping and every instrument could be clearly distinguished from the others. This is, however, most likely the effect of using preset synthesizers, which have usually already been optimized and require very little mastering knowledge to use effectively. Apart from that, the piece is quite 'crowded' with instruments.

If I were to give you a single piece of advise, it would be to study some music theory first. A lot of people start writing music with no music theory knowledge whatsoever, hoping it will come to them simply 'by experience'. While this is slightly true in some regards, you can greatly improve your skills simply by just immersing yourself in the technical things 'behind' the music.

That said, I wish you the best of luck with your future productions!

All in all, 2/5 stars.