kbd here to tell you the good and the bad of Super Paper Mario in as few words as possible. ;)
The good:
+ 10 - 20 hours approx. single player mode augmented by fun mini games and optional challenges
+ charming and genuinely funny
+ clever puzzles
+ good artistic design (graphics and sound)
+ great characterisation and story
+ platforming and light RPG elements are in nice constrast
+ unique 2D - 3D mechanic
The bad:
- bosses are too easy
- lots of dialogue
- some backtracking and repetitive segments
