Remember that diamond commercial with the young couple in the park looking longingly at the elderly couple walking past them holding hands? Someone’s gone and turned it into a feature film — splicing in a good chunk of “Under the Tuscan Sun’’ for insurance — and what was touching at 30 seconds is a groaner at 105 minutes. 
 
 That’s not entirely fair. You don’t have to be 13 and a tapioca-brained romantic to enjoy “Letters to Juliet.’’ But it would help. 
 
 The movie’s the second heart-tugger in three months to feature Amanda Seyfried (“Dear John’’), the latest ingenue to be anointed an up-and-coming star. Honestly, there’s nothing wrong with “Juliet’’ that a better, deeper actress wouldn’t fix. (And a script. A script would be nice.) With her platinum waterfall of hair and big tweety-bird eyes, Seyfried offers a vision of youthful loveliness that ceases the moment she opens her mouth to deliver lines in the broad, affectless tones of a weather girl. 
 
 She plays Sophie, a fact-checker at a spurious Hollywood version of The New Yorker (Oliver Platt’s her harrumph-y boss) who heads to Verona on a pre-honeymoon with her fiancé and gets sidetracked on a story. Drawn to the lonelyhearts notes pinned to the courtyard wall at the Casa di Giulietta — supposedly the home of the real Juliet Capulet of “Romeo and Juliet’’ — Sophie discovers a 50-year-old letter hidden behind a brick and decides to answer it. 
 
 The letter was written by a young Englishwoman named Claire, heartbroken over leaving her Italian one true love. On receiving Sophie’s reply, Claire descends upon Verona in the person of Vanessa Redgrave, who exudes so much grace, talent, and class that Seyfried is immediately reduced to an acting-school Munchkin. Really, the movie itself never quite recovers. 
 
 Claire has brought along her skeptical grandson Charlie (Christopher Egan), and the threesome scour Tuscany by car for the lost love, one Lorenzo Bartolini. It turns out there are many, many Lorenzo Bartolinis in the area, and the best joke in the movie is that they’re all willing to pick up with Claire where they never left off. 
 
 Sophie and Charlie hate each other, of course, which means that they love each other, of course. “Letters to Juliet’’ clanks along the tracks of romantic-comedy confusion with grim predictability: The moon is always full and the Italian locations are gorgeous, or would be if they weren’t overlit like a trattoria poster. But maybe it’s wrong to expect Continental nuance from a film that ends with a Taylor Swift song. 
 
 The larger problem is that the central duo is just plain dull. Egan’s Charlie is a wooden Englishman and Sophie is a gauche, underwritten character that only an Anne Hathaway might (I say might) be able to flesh out. When Claire asks her grandson, “How many Sophies do you think there are on the planet?’’ it’s difficult not to think, About 6 million on the East Coast alone. That’s probably why the movie will be a hit. 
 
 Adding to the general air of absurdity, the fiancé — an excitable, self-absorbed chef named Victor — is played by the Mexican actor-hunk Gael Garcia Bernal, and we’re asked to believe that any sane woman would throw this guy over for the stiff-backed Egan. Victor loves wine, cheese, truffles, life, and for that the movie punishes him. 
 
 It punishes us with dialogue to make a Nicholas Sparks fan wince (“When we’re speaking of love, it’s never too late . . . ’’) and Gary Winick’s mechanical, uninspired direction. Late in the going we’re treated to a reunion of Redgrave with Franco Nero, the Lancelot to her Guenevere in 1967’s “Camelot,’’ and the ease with which these two portray mature passion is deeply touching. If only the movie were interested. “Letters to Juliet’’ makes the case that even boring young nincompoops deserve love. For the rest of us there’s always Tuscany. 
 
 Ty Burr can be reached at tburr@globe.com. 
 
 © Copyright 2010 Globe Newspaper Company. ||||| "Letters to Juliet" is a by-the-numbers romantic comedy -- and I mean that in a good way. Sure, the story merely puts attractive, likable people in a pretty setting and lets love take its course. But lordy, that is a breathtakingly refreshing change from the spate of recent rom-coms hell-bent on delivering flinty females and douchebag dudes in situations that require lots of yelling. 
 
 In contrast, "Letters" gives us the radiant Amanda Seyfried as Sophie, an aspiring writer who does not need to be taken down a peg. On vacation in Verona with her restaurateur fiancé Victor (Gael García Bernal), Sophie discovers a 50-year-old letter to Shakespeare's tragic heroine nestled in the city's famous romantic wailing wall -- and impulsively replies. What follows are two sweetly engaging romances -- the quest of British pensioner Claire (Vanessa Redgrave) to reunite with her long-lost soul mate, and her uptight grandson and chaperone Charlie's (Christopher Egan) blossoming affection for would-be cupid Sophie. 
 
 "Bride Wars" director Gary Winick isn't exactly reinventing the form here -- "Letters" will hardly go down as the funniest or sharpest caper of the year. And I confess I had a hell of a time getting past the conceit that the sexy, exuberant, feeds-his-girlfriend-delicious-cheese Gael García Bernal is somehow supposed to not be the leading man here. (Note to Hollywood: If you made a movie just about Gael García Bernal and cheese, it'd do better than "Avatar.") Are we really supposed to believe Sophie would lose her heart to the relentlessly bland Egan, a performer my screening room companion noted "doesn't look like he has pubes"?
– Critics aren't exactly head-over-heels for Letters to Juliet, a predictable romantic comedy about a young woman helping an older one reconnect with a lost love, but it has its charms. Here's what they're saying: “Letters will hardly go down as the funniest or sharpest caper of the year,” writes Mary Elizabeth Williams of Salon, but it's a “breathtakingly refreshing change” from the “flinty females and douche-bag dudes” that populate most recent rom-coms. “Letters to Juliet makes the case that even boring young nincompoops deserve love,” writes Ty Burr of the Boston Globe. Maybe, maybe , a better actress could have made it work, but Amanda Seyfried “delivers lines in the broad, affectless tones of a weather girl.” This movie is “an insult to common sense and the hacks over at Team Harlequin,” writes Kyle Smith of the New York Post . “Not to be left unsaid are lines like, 'Destiny wanted us to meet again,' 'An angel brought you to me,' and 'When we are speaking of love, is never too late.'” But that's fine, writs Kerry Lengel of the Arizona Republic. It's not date-night material, but “Letters to Juliet is a guilty pleasure for the ladies, perfect Blu-ray fodder when their significant others turn them into World of Warcraft widows for the evening."