Plenty of "woo-hoo"s, but also a few "d'oh"s
The answer: It's good! ...Mostly.
The Simpsons Game has one of the strangest, most interesting, and most self-referential plots I've ever seen in a videogame: The Simpsons discover they're characters in a video game, and they have special video game powers that they put to use fighting their way through their latest licensed adventure. The cutscenes have some the most hilarious Simpsons material I've seen in some time, written and performed by the staff and cast of the show. Thank you, EA, for actually getting them for this game. Even during gameplay, the cel-shading of the characters and environments keeps it looking just like the show, albeit all polygonal-like.
The Simpsons each have powers that suit them well: Bart transforms into Bartman to use superhero-like moves like gliding and using a grappling hook. Homer can eat food to turn into a big fat ball of destruction or eat gummi snacks to become a gummi blob. Lisa stuns enemies with her saxophone and summons the Hand of Buddha to move parts of the environment and pound enemies. Marge can rally NPCs into a mob and get them to do her bidding in a sort of Pikmin-like manner, as well as send Maggie into crawlspaces to get to out-of-the-way switches.
Also suitable is how Bart and Homer, the two better members of the Simpson clan (in my opinion) got the better powers. Bart can get to all sorts of places with his gliding, grappling, and so forth, not to mention with his slingshot, he's the only character with a projectile until Homer gains one late in the game. Homer's transformations are a force to be reckoned with and fun to use, though reliant on food pickups. Lisa and Marge, on the other hand, have basically the same, not-that-combative powers over the whole game. I mean, Lisa's Hand of Buddha gains some attack powers, but she still needs to find a meditation spot to use them, and some of these spots leave her open to attack while she's using them. Marge can get her mob to attack, but they're not that reliable at it, either spending too much time trying to chase the enemy down or getting their own butts kicked, forcing Marge to beat the enemies up herself.
Each level, barring the Homer-only tutorial, gives you two Simpsons to use, allowing you to switch between them as their powers are needed, or you can play co-op with another player. Both methods have their hits and misses, though. Playing one-player, there are times when you need to have your partner stand in one spot while you do something. The AI is usually good about this, but other times, when you switch to the other after putting the first in position, that character will leave their post and come running. Other times, you want the other player to be following you as you progress through the level, but when you get to a point where you need the other, you find out that they've just been standing there where you left them the whole time, so you have to cover the same ground again as the slacker once you switch to them. Plus, the one that went ahead is likely to come running back towards the slacker once put in AI control.
In co-op, both characters are under player control, with eliminates this problem, but there are often times when just one character's powers are needed, usually to open the way for the other, while the other character is left just standing there or fighting off a horde of enemies by their lonesome if they weren't cleared out in advance. For example, most Bart-and-Homer levels have areas where Bart has to jump and glide around most of the area to find a switch that will open a door or drop a ladder for Homer to use. But that whole time, there's nothing for Homer to do but stand around and scratch his butt. In single-player, you can always be in control of the Simpson that needs to do something, but in co-op, most of the time will have one of the players waiting on the other.
The level layout is platformer-style, but the camera tends to make things difficult. It's usually not in a good position to judge jumping distance and keeps getting stopped by environmental objects when you try to swing it into a good spot. And even after you align it right, it often moves back the second you take a step forward, if not right away. It doesn't help that the Simpsons aren't the best jumpers either, though maybe playing Mario games my whole life has just raised my expectations of platforming ability. Even during combat, enemies keep going off-screen and throwing projectiles at you from there.
As I said before the cutscenes are hilarious, but there's plenty of funny quips during the gameplay too. The characters will poke fun at everything about video games, from the clichés to the culture to the industry itself. Enemies get some funny lines in, like aliens asking each other if they look fat "because I feel bloated", and some levels have announcers for one reason or another, such as the museum observatory narrator who slips remarks about his ex-wife into his narration. Sometimes, though they talk just a little too much. For example, as Marge's levels involve building up a mob that follows her around, that means there's constantly a bunch of NPCs near you that WON'T SHUT UP.
The game's only a couple of hours long, but even after you beat it, you can go back and replay the levels to find collectibles and video game clichés. The Wii version also includes two unlockable "Wii Moment" mini-games: Bite Night (fun) and Bart Wings (lame). However, from what I've been reading around the Internet, the other new-gen versions of the game have much more content than the Wii, including some sandbox mode where you can freely roam around Springfield. Also, the Wii's motion controls tend to not respond as well as they should, particularly when trying to shake both the remote and nunchuck to active a character's super attack, only to get no results while your character just stands there open to enemy attack.
Despite its obvious issues, though, The Simpsons Game is actually pretty enjoyable. It's great to see that EA chose to go the extra mile to make sure the game captures the spirit of the show instead of just making some lazy cash-in like so many licensed games have been, and Simpsons fans will definitely appreciate it. The Wii version is okay, but if you have a 360 or PS3, you might want to get it for one of those.