Really good, with some flaws.
There were a few big problems I had with this game. The first and most important was the fact that if you died at any point, you had to do everything over again, and the first level is long and boring. The text was spelled pretty poorly, and it was really hard to get energy resources, which was a big pain in the ass when you had a bunch of your turrets mowed down by the enemy, and then had no ability to replace them. Also, there weren't any battle sounds at all (although I'd probably like the option to turn them off if they got tedious, like the music.) I do think that sound effects would have been good for this game though.
If you look over the discrepancies, though, this was a really great game.