I typically don't like turret defense games like this, but this was very enjoyable. The designs of the guns, buildings, and ships, robots, or whatever the hell those things were were original as far as I'm concerned. The colors were pleasing as well.
The music was nice, if somewhat repetitive, was great. Mainly, I don't like the lack of sound effects, it would've made it a lot better.
Another thing I didn't like was the "buffs."
I don't like the idea of instead of upgrades, you replace a turret on your base with some massive hunk of junk that increases health or damage. I'd rather just have upgrades.
Anyway, the game got very repetitive eventually, and started to be more of a kick in the balls at the later levels. It may have been a well designed, well executed kick in the balls, but at the end of the day, you're still walking funny.