(CNN) -- After 18 years and 400 episodes of a show that refuses to grow old, "The Simpsons" finally graduates to a movie theater near you. It doesn't take Homer long (about two minutes) to ask the obvious question: What kind of sucker pays for something he can watch at home for free?
To escape troubles in Springfield, Homer Simpson moves to Alaska -- which brings other problems.
Thankfully this is the last time the thought will intrude on what proves to be a smooth and assured transition. Clocking in at just under an hour and a half, "The Simpsons Movie" is basically a bumper edition of the show; bigger, longer and uncut. (Newsflash: We get a passing glimpse of Bart's manhood after Homer double-dares him to skateboard through Springfield butt naked.)
Fans will be relieved, mostly. And latecomers should get an idea of why this rudely sketched animated sitcom inspires such widespread devotion.
At its best, "The Simpsons" is as cruel a satire on American culture -- or the lack of it -- as anything on prime time. Producer James L. Brooks negotiated creative independence from the Fox network, and over the years creator Matt Groening and the show's writers haven't been shy to bite the hand that feeds them. Indolent blue-collar imbecile Homer may not be a model citizen or a working-class hero, but you have to look next door, at his squarely middle-class, born-again neighbor Ned Flanders to find where the slap invariably sticks. Interactive: "Simpsons" 101 »
Not this time, though. Evidently convinced that the key to sustaining a motion picture is in the liberal use of epiphanies, Brooks, Groening and company kick things off with Grampa Abraham Simpson getting a divine revelation, a message from God right in the midst of Holy Communion ("Terrible things are going to happen ...")
This warning seems to refer to an impending environmental catastrophe and/or Homer pigging out with his new pet porker. Either way, it goes unheeded by the nominal head of the family, whose concern for the earth's resources rarely extends beyond his next doughnut. When it comes time to dispose of his pig's waste, Homer takes it over to Lake Springfield.
Meanwhile, perhaps cowed by his public humiliation and jealous of the hog, son Bart begins to draw unflattering comparisons between Homer and Flanders.
Even wife Marge has had enough, after Homer's made it clear he cares more about his own yellow skin than the good folk of Springfield. After all, the latter are doomed by the overzealous response of President Schwarzenegger's Environmental Protection Agency, which plans to turn the town's toxic embarrassment into a new, improved Grand Canyon ... eventually.
The show has ventured beyond hometown security before, of course, but it's usually sharper on the micro: domestic squabbles, neighborly feuds and the petty prevarications of municipal authority figures. Let's face it, the Homer Simpsons of this world have no curiosity for anything beyond the remote control, so it's a stretch when he pulls a poster of Alaska out of his back pocket and promises a fresh start.
The family hightails it out of Springfield and almost immediately the movie loses some of its sparkle. Homer's odyssey gives the picture epic scope, no doubt, but it's a pity several well-loved supporting characters are reduced to bit-part status as a result, and dare we suggest his redemptive transformation from pathetic Every-jerk to mock action hero is a teensy bit tired?
That's not to say "The Simpsons Movie" doesn't have plenty of laughing gas left in its tank. But those hilarious opening 20 minutes remind us how far this wickedly funny animated series pushed the sitcom format toward an inspired, anarchic subversion. The movie settles for something more conventional, so maybe those claims "The Simpsons" has aged some have a point.
Nevertheless, nobody should have a cow. Bigger and longer don't always mean better, but "The Simpsons Movie" is still a cut above.