If you're a fan of The Simpsons then it's a must have title, in my opinion. I'm a huge fan and I love the game. If you're not into The Simpsons, I'm not sure you'll appreciate it as much, but it's still a good game.
The humour is first class, and the parodies' of other games are excellent. I'd point you in the direction of the demo, but I don't think it does the game justice, to be honest.
I'm sure other people will give you their opinions, too
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Phenom