The gameplay is quite good, and makes no assumptions on what the player knows. The art-style is slightly simplistic, but it does fit the theme nicely. Difficulty wise... I'm sticking to FPS games (I couldn't beat level 3). I think this was mostly because of the one-block openings that you have to weave through and partly because of the movement speed of the enemies.
Overall, it was a great experience, especially with the gameplay!