At least it's got personality
The story itself is one of the games strongest aspects by far. Raz is a very endearing character, and the fleshed out cast are complemented by a colorful tale. To match the oddball humor the game is soaked in is the occasional dark, demented edge. A lot of the characters you get to explore during the game have some serious demons in their closets, which make their psyches all the more interesting to explore.
Unfortunately, Raz and crew are dropped onto rocky gameplay terrain. Being a platformer, there is a spotlight shined on the quality of play, and a lot of blemishes are exposed. The first few levels lend themselves to standard platforming fare and play well enough. However, as you progress and earn more powers, a higher emphasis is placed on combat, which becomes an obvious weakspot for the gameplay. Continued gameplay variation keeps the ball rolling, though most of it consistently ends up being bland or clunky.
The middling gameplay is extra unfortunate since the settings and situations that Raz encounters tend to be resoundingly unique and memorable. The popular Milkman Conspiracy portion sums up the issue well; a fiendishly clever and comical scenario wrapped around a dull gameplay experience.
Psychonauts is an easy game to cheer for, and many hold it in high regard for good reason. It has a great sense of humor and tells a memorable tale throughout bizarre set pieces. All of this does enough to carry the game through moments of frustration and dull gameplay, which did indeed become very irksome rather frequently.