The latest adaptation of a Nicholas Sparks novel gets a jump on the Valentine’s Day competition this week.

Like the rest of Sparks’ work ("The Notebook," "Nights in Rodanthe"), the tone of "Dear John" is bittersweet. Sparks is the current master at tossing likeable characters into a great romance, then refusing to allow them to be completely happy.

The romance in "Dear John" begins when Savannah (Amanda Seyfried) drops her purse into the ocean while hanging out with friends on a pier. John (Channing Tatum) sees this and valiantly dives into the water. He then casually walks onto the beach clutching the purse, water dripping off his pecs and abs like some incarnation of Poseidon.

I dwell on the scene because it’s a wonderfully romantic moment, but also because the movie features many similar scenes with Tatum walking around shirtless. This will make many of you very happy.

John and Savannah fall in love instantly. On their first date, Savannah declares that she wants to meet John’s father. That night.

Mr. Tyree (Richard Jenkins) has Asperger’s syndrome, which has always been difficult for John, especially since his mother is gone. But Savannah’s neighbor Tim (Henry Thomas) has an autistic son, and she relates very well to people with developmental disabilities. What could possibly go wrong with all this, right?

John is home on leave from the Army and must return after two weeks. John and Savannah promise to marry when his tour is over, and they vow to keep in touch by exchanging letters constantly.

The letters give us our title and become the centerpiece of the movie. While this is totally plausible and works well in a novel, it does not translate to a movie screen.

Long stretches of "Dear John" consist of John and Savannah sitting and looking at the letters as we listen to them read in voice-over. This is even more boring than it sounds.

The letters drag the pace of the movie from beginning to end. To be fair to director Lasse Hallström, since the letters are the central device of the novel they would have been an inescapable burden for any adaptation.

Hallström’s career has been wildly inconsistent in quality, ranging from the outstanding "What’s Eating Gilbert Grape" and "Chocolat" to the awful "The Hoax." His movies aim for the heart and tend to be understated. He focuses on characters’ emotions and quiet moments rather than going for big, operatic peaks. His style suits "Dear John" well, but it certainly doesn’t add much excitement to what is already a muted story.

In many ways, "Dear John" delivers exactly what fans of the genre want. Seyfried and Tatum are gorgeous and share chemistry. Jenkins has officially hit his stride. After earning wide praise for "The Visitor," he gives a perfect performance as a father who loves his son but lives with a disability that prevents him from expressing it.

A good romance needs to have a plausible obstacle keeping the boy and girl apart, and this movie has a simple, realistic source for its heartbreak.

And "Dear John" includes one perfect scene, which is more than we can say about most movies. Tatum nails the tragedy of the scene, and Hallström’s subtle style complements the acting beautifully. If this scene doesn’t inspire tears, you might want to check for a pulse.

But viewers will be sharply divided on the ending, especially all the Sparks fans. The final act of the movie strays from the novel significantly. Not only that, the final scene is clumsy and tacked on. It’s the kind of ending that producers force a filmmaker to add after a bad test screening.

Even with its flaws, though, this might be the best romantic drama of the year, mostly because we simply don’t get many good romantic dramas.