I liked it a lot. Partly through the game I was getting sick of all the creaping sections and there was a few times where I died because of the camera, but its good.
The characters are good although more of a backstory would be nice and and voice acting is strong, although if you talk to anybody in the game you will be given some text to read instead of hearing voiceover.
I think this kind of episodic game with a self contained story, but one with possible sequals, is the future of gamming. That and making games cheaper to produce would catapult the industry forwards to a bright future, but that is NOT what is happening and it is a shame because there should be more games like Beyond Good And Evil.
4/5
Incidentally if you liked Beyond Good And Evil, you will like Psychonauts. I know it isn't out yet, but the demo was very positive.