Even though it's let down by longevity and a lack of ancillary options this still plays like a classic and is one of the best new shooters of its generation.
Pros: Superbly crafted controls and mechanics that feel unlike any other shooter. Some great weapons and enemies. Excellent pacing and level design.
Cons: It's short (or at least not long) and there's no multiplayer. More unforgivably there's relatively little to unlock or do beyond the first play through.