The graphics and sounds are appropriate.
The gameplay is kind of boring after like 200 points. When you find out that the ghosts keep blocking on the buildings, you can just stand in the corner and spew bullets at the incomming waves, and count the points as they go.
There is no feeling of progress, no levels, no upgrades, no enemy variety, no nothing, so the game's kind a boring...
But there were some good design decisions, like you don't have to click, you can just hold mouse button to shoot. Also the camera felt good, it followed the crosshair nicely.
The game suffered on performance, there was a big slow-down after a few minutes, when a large group of ghosts piled up.
The AI was very stupid, take your time learning about Navmesh from unity, it can really increase your AI level at a very low cost, it's really simple to set up.
But the game played better than most games of this kind on this gamejam, congratulations. The controls felt very responsive.