It’s official. Reese Witherspoon is the new Meg Ryan.

That means Witherspoon has the charm, sparkle, and impeccable comic timing to keep an entire movie afloat and make it look effortless. She makes watching it seem effortless, too. That’s a good thing, because it takes every bit of her talent and all-around adorability to keep it aloft, considering the considerable weight of its uncertain script. Without her, even the enticing premise and an exceptionally able supporting cast would sink under the weight of a plot that somehow manages to be both predictable and disjointed (I’d bet a bucket of popcorn that there was some serious recutting along the way).

Witherspoon plays Melanie Carmichael, a fashion designer just breaking through to the big time with her first solo show. Not only is it a huge success, but she also gets a swooningly romantic marriage proposal from a gorgeous, thoughtful, supportive man who adores her – and who happens to be the son of the mayor of New York (Candice Bergen).

It’s the 21st century Cinderella dream come true, except for one hitch — literally. Way back when she was just Melanie Cooter of Pigeon Creek, Alabama, she got herself hitched to her childhood sweetheart, and now she needs to get herself unhitched so that she can be free to marry Prince Charming.

So, she goes back home for the first time in seven years, and she finds out that you can take the girl out of Pigeon Creek, but you can’t take Pigeon Creek out of the girl. Her accent comes back, and, more disconcertingly, so do some of her feelings for her husband, Jake (Josh Lucas).

The movie spends too much time reuniting Melanie with people from her past. There’s a lot of “Melanie? Is that you, girl?” It also spends much too much time introducing us to all kinds of adorable cracker stereotypes without much payoff. It wastes time on a tired plot twist about Melanie’s exaggeration of her family’s social standing that even the movie’s characters seem bored with. But Witherspoon is such an unquenchably winning presence and such a fine actress that I defy anyone to watch it without smiling.

A terrific soundtrack also helps, with a cover of the irresistible title tune and delicious songs by country greats. Lucas and Dempsey are both dreamy enough that even movie-savvy viewers may find it hard to pick the winner. Director Andy Tennant (“Ever After”) delivers a romantic comedy that should be able to hold a strong position at the box office until the next Julia Roberts movie comes along.

Parents should know that the movie has brief strong language, gay characters (one out, one closeted) who are positively portrayed, and references to an out of wedlock teen pregnancy. Melanie gets drunk (and gets sick). Drinking, vandalism and minor crimes are portrayed as evidence of a free spirit.

Families who see this movie should talk about why people are tempted to lie about their past, and how they would respond if they found out someone they cared about had lied to them. What does Melanie mean when she says “I figured if I was pointing at you, no one would see through me.” What didn’t she want them to see? What is Melanie likely to do next?

Families who enjoy this movie will also enjoy, “The Runaway Bride” and “Never Been Kissed.” They should also check out the wonderful classic with a similar plot, “I Know Where I’m Going.”