If you liked the show, buy the game, if you don't like the show and than don't.
Gameplay:
You get to play as Homer, Marge, Bart, Lisa, each character has a special move that the other character doesn't have, the game basically is spoofing video games, with this thing where you get to places that have "Video Game Cliche's" which are, nonetheless fun to collect, there's a stage called "Enter The Cheatrix" and Bartman Begins which are obviously stages that are supposed to resemble and spoof a certain movie or video game.
One thing I just found out and made me really annoyed is that they took out the Free-Roaming, I mean you can roam all you want in the house, but you can't go outside and do what ever you want like in "Simpson's Hit N' Run" and I'll take a certain amount of points out of the score for this, because I wanted some Free-Roaming in the city.
In "Hit N' Run" I was going around exploring places and that was very fun for me when I wanted to take a break from the missions, I havent finished the game to ACTUALLY know that they're is no Free-Roaming, but I finished two levels and so far, nothing.
But all this game has some aspects that are better than Hit N' Run, which are the ACTUAL missions, the missions and objectives that you had to do in Hit N' Run were very boring, and that's how I feel about games like GTA, I only played GTA Vice City on the PC, I usually NEVER play the missions, I just run around exploring and hitting people and stuff and I know that gets old, but I probably clocked over 30 hours on GTA Vice City without actually doing ANYTHING.
But the Camera Angles in The Simpsons Game were bad and annoyed me sometimes.
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Graphics: They were pretty good, nothing too amazing, just good for a PSP game.
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Enjoyability: You will enjoy this game, I think people who love the show should pick it up for 50$, I am not kidding people who love the show will love this game, I really like the show, but I only watched and own the first and second season of the show on DVD and I like it and I recognize the characters and such, and I got the game for 20$ so that's good I guess.