Time has been less than kind to Shrek, the endearingly ornery ogre from the land of Far, Far Way, where the villagers who once feared his quick temper now see him as a cuddly tourist attraction.

In Shrek Forever After – billed as the fourth and final installment of a franchise that has earned more than $1.5 billion in the U.S. alone – he is mired in the malaise of monotonous routine, both as a diaper-changing father of three and as a monster who’s tired of being Mr. Nice Guy.

Worse yet, he is stuck in a story short on magic, the key ingredient in any fairy tale. DreamWorks animators have kept their beloved beast in step with the expectations of audiences dazzled by the 3-D revolution, with a flair that invigorates the movie’s aerial action sequences, but technical wizardry isn’t all that’s required.

Will kids love it? I believe they will. Forever After is competently crafted and briskly paced, with closing credits long enough to nudge it just past the 90-minute mark. The story is involving, to a point: Yearning to revisit his rambunctious youth, he makes a deal with the devious Rumpelstiltskin (voiced by Walt Dohrn) to feel like an ogre again – to terrify the townspeople and run roughshod through his precious swamp.

Little does Shrek (Mike Myers) realize he’s gambling with his life. Hidden in the fine print is a typically ’Stiltskinian clause that erases the grumpy green giant from the history books altogether. He returns to Far, Far Away a pariah, and relishes his renewed notoriety. But where is Fiona (Cameron Diaz), his princess? And why do best friends Donkey (Eddie Murphy) and Puss in Boots (an impeccably coy Antonio Banderas) treat him like a stranger?

Thus begins a modestly diverting yarn, inspired by Frank Capra’s It’s a Wonderful Life, that finds Shrek stranded in an alternate reality in which he was never born. Rumpelstiltskin is king. Ogres are hunted by broom-wielding witches. And Fiona is nowhere to be found.

There is little suspense in Shrek’s quest to reverse this sorry turn of events, but even as his latest adventure coasts toward its happily ever after, we get flashes of the zany inspiration that made Shrek (2001) so refreshing. (Preparing to ambush the tyrannical ’Stiltskin, one ogre, voiced by Craig Robinson of NBC’s The Office, suggests a chimichanga stand on the battlefield. No sense in fighting on an empty stomach.)

Yet ingenuity, and an appropriate sense of wonder, is too rare in this mildly amusing fantasy about a midlife crisis. We can’t shake the feeling that Shrek, like the storytellers guiding his familiar journey, is going through the motions. That might be enough to satisfy the kiddies, but for their parents, a story this slight might prove a tougher sell. Best put the big guy to bed before he’s too tired.