Although simple, PixelJunk Monster's visuals are clean, crisp and appealing. The art style has a basic look that is somewhere between watercolors and cel-shading. Lines are crisp and black, but the coloring has a blurry look. Everything has a unique look; your avatar looks like a hybrid of a tiki-god and a turtle, while the monsters range from small spiders to bats to big, burly, gorilla-like monsters. Best of all, even with dozens of cannons and monsters on the screen, there is never a hint of slowdown.
Sound is low-key, but in a relaxing way. Even as a group of 20+ monsters threaten to crush the citizens you are protecting, the background music is low and melodic. The only disappointing aspect is lack of sound effects; but even this isn't a major deal considering more effects could have ruined the atmosphere created by the music.