It's a well-made game with a good idea at the base. It also has a good premise and scope, and an atmosphere which is functional to that; the various game elements feel very cohesive. I like it overall.
There are 2 big flaws for me. The first one are the randomized, endless levels. I would have much preferred an adventure mode with "handcrafted" levels which have a beginning and an end, as this would allow for a more refined difficulty and a more sofisticated level design, which, as it is, is far too simple.
The second one is that the fundamental game mechanic doesn't allow for a much deep gameplay, it's too simple and more suited for a mobile game.