I bought this off GOG because of the unanimously positive reviews. There is no doubt to me that this is a very nice game. It's very polished and engaging, with a nice story and great characters.
That being said, it's not perfect. For one thing, I found that the gameplay, while entertaining, takes the back seat in this game. It's very simple, and turns out to be quite repetitive eventually. It's also a short game, with little replay value.
What makes the game shine is the visual and audio presentation, coupled with the very streamlined design. Beyond Good & Evil is a game that has aged extremely well, the cartoon graphics still feel fresh while succeeding in bringing the characters to life.
Overall, I recommend trying out this game. It doesn't do that much in the end, but it's the sort of game that you just can't help but enjoy despite its flaws.