pretty, but bad controls and silly mechanics
Graphically, it looks OK, but there are far nicer looking Geometry Wars clones out there.
My main gripe with this is the controls. Simply put, I want to control the ship with keyboard and aim with the mouse. Controlling movement and aim in a 360 degree shooter with mouse is stupid. It is not a challenge. It is not difficult. It is bad control design. Please, add keyboard control for movement.
Getting struck once removes all upgrades. This is a problem because of the aforementioned point - the controls for this game are terrible. On the initial levels, this doesn't matter, as enemies die with very few shots. But on later waves, it turns the game into a long, drawn-out borefest. Again, this is not a challenge or a matter of difficulty. It is just bad design.
The ability to switch firing types is good. You get points for that. The bomb system is fairly simple. I don't see why you should have to hold down the mouse for that, though - it delays what should be a reflexive action. Instead, that should be a single click or keystroke.
The upgrade system is silly. You're supposed to collect these yellow things, which is easy enough, because they move towards you over time. However, there are two problems. The first is that they fade over time. This is a problem due to the bad control scheme, which means you'll be shooting and killing stuff you didn't intend to, meaning wasted yellow thingies. Again, not a challenge or matter of difficulty, just bad design. Next, the game doesn't tell you your progress to the next upgrade . Given that it apparently takes a very large number of these, there should be some indication that the player is approaching the next level of upgrade. A simple progress bar would work.