This is a great little game. I admit I was disappointed at first to see no mouse compatibility in-game, it's played entirely with keyboard. Just a preference of mine I always hope to see, but I shouldn't be surprised there isn't one here.
I only encountered one small bug with the in-game pause menu but this may only be an issue for me.
There is a huge lack of options under the settings with just fullscreen on/off, difficulty, key bindings and one other which I don't know what it is. This doesn't bother me at all, but is something others might want to take into account.
There is no customization for your ship whatsoever that I can see. Powerups are temporary and primarily obtained by destroying enemies, otherwise there is no weapon or ship upgrades. You can flip your ship around for slower, more accurate attacks and dodging. The dodging seems forced in some areas however to get you to actually use your ship on it's side, because it's very easy to just leave your ship flat and spam the two, faster guns.
Also I didn't seem to notice a scoreboard, though I did notice something about my score being uploaded. I'm not sure if there's a place online to view leaderboards; it would be nice as that is the game's point.
I'm giving this a thumbs up, why? Because for it's price this game is an amazing grab. The controls are responsive, the game is pleasing to look at; the hit-boxes are forgiving, maybe too forgiving for your enemies, but that can just add to the challenge. So there's only one level? So this is only $2.00 and I think a lot of work went into this for that price despite what it lacks. I'm enjoying this game for what it is, who isn't going to give a game a thumbs up if they're enjoying it?