A very enjoyable game, good graphics, diverse ships / weapons and a well judged progression of difficulty.
The only thing that is really bugging me is that the "miss" count seems a bit buggy. Maybe I'm just missing something obvious here, but I've gone through certain levels many, many times and clearly killed every enemy that comes my way, but then out of nowhere my miss counter will jump up. It makes it really frustrating when I'm trying to get an A or S grade. Besides that, more options for upgrades would be neat, as I found myself maxing out every possible upgrade about 3/4's through the game, so some more customisation would make things more fun IMO. And like the poster below me said, left over bullets from the bosses are a bit of a pain.
Eitherway, it's a solid game and one of my favourite top down shooters.