Over the course of time, The Simpsons became less about the actual Simpson family, and more about the town itself, so in order to make a great Simpsons game you need to have a great Springfield, and this is the best one you're going to find.
I briefly described the Springfield residential area in part 1, but now I'm going to go into more detail. Despite the fact that the show often switches areas around for convenience, but I like to imagine that this is how the city actually looks. The fact that. I mentioned the areas that you expect to see, like The Simpsons' and Flanders' homes, Krusty Burger, the Kwik-E-Mart, etc. But in addition to the actual buildings, you'll also see little touches like the billboard from the episode where Springfield changed area codes, delivery trucks carrying copies of Bonestorm, and Jasper frozen in the Kwik-E-Mart freezer.
The second level finds Bart in what I suppose would be called the business district of Springfield. You start in front of City Hall, greeted by Jebediah Springfield's statue. You find Milhouse nearby and begin your first mission of the area. One thing that I thought was very smart was that the first mission in each level requires you to make several stops throughout the city, giving you a basic lay of the land for future missions. Throughout your tour of the city, you'll see such familiar locales as the DMV (which you can enter to find Patty and Selma), the Try N' Save, the broken down Springfield Monorail, the dog track where the family found Santa's Little Helper, the Springfield Googleplex, the Duff Blimp, and Springfield General Hospital. The downtown area is my least favorite in the game, it just seems kind of drab, lots of grays and purples. The Springfield residential level is charming, and going through it is like returning to your hometown after you've been away at college, it's just the way you remember it, and the Squidport/Downtown area is where you'll find lesser known but more interesting locations. The business district, however, has a lot of sharp turns and traffic, and it seems like whenever you're on the Matlock Expressway, other drivers make it a point to change lanes in front of you, which is a major pain when you're on a timed driving or racing mission. It's also the most convoluted area, and the only one where I don't always know where I am or how to get to a certain area.
Moving on to the downtown area (Levels 3 and 6), you can make one lap around and see locales from at least 20 different episodes. It's the smallest of the three but probably the most dense. Here, you'll find recurring locales from the show, like the Android's Dungeon Comic Shop, Barney's Bowl-a-Rama, and the Aztec Theatre, but you'll also find buildings from classic episodes like Kamp Krusty (which is the only thing in the game that feels out of place), the Observatory, the Duff Brewery, Wall-E-Weasel's, and you can even ramp over the Ring of Fire/Ring of Ice/Dog Doo Stick (even though that was actually located in Las Vegas in the show) to land just outside of Mr. Burns' Casino and make your way to the Springfield Squidport.
Having the game segmented into different levels using distinctly separate sections of Springfield was an excellent choice here. I don't feel like it would have worked if they went the traditional open-world route and opted to have all of the areas connected, simply because they're all so different from one another. I still prefer the Springfield residential area in Hit & Run to The Simpsons Game. Here, it may not be as detailed, but it's a much larger area and the amount of small touches and Easter eggs that they scattered around make it so much more enjoyable. In The Simpsons Game, Evergreen Terrace and the surrounding areas are basically just there as a stopover between missions and serve very little purpose.
So there's a basic run down of the things you can expect to see in the three different areas. Three areas may not sound like a lot, but they're dynamic enough to where when you revisit an area for the second time (or third time) there are enough little changes to keep it enjoyable, like the church marquee changing, or the different sight gags that occur when you enter the school. I mentioned in part 3 how level 7 gets really creative because Springfield becomes it's alternate Treehouse of Horror dimension. Pedestrians are replaced with the undead, police cars become hearses, the Kwik-E-Mart becomes the Spook-E-Mart, and so forth. Kang and Kodos' ship crashes into the nuclear power plant, and if you can manage the stubborn camera and tricky platforming, you can work your way up the wreckage and into Mr. Burns' office. Mr. Burns has always been my favorite character in the show, and his office comes complete with his trademark trap doors and his stuffed polar bear from "Homer the Smithers."
I took notes while replaying this game just so I wouldn't forget any notable references, and by the time I was finished, I had over 7 pages full. If I listed every reference or gag I came across, we would be here all day, and I'm' sure there's still things in there I've missed, that's how full of love this game is.