I like this type of games so the first impression was already good.
It's really enjoyable and the graphics are cute. I like the fact that this is not a mere "move around while the game plays itself" survival but you have to aim and guide your attack everytime.
One thing that I missed was that I could not set the screen bigger. If I switched to fullscreen to see more enemies and a bigger chunk of the map at once, it didn't expand.