In the film, based on the Italian movie L'Ultimo Bacio, Michael has a gorgeous girlfriend, a lucrative career as an architect and a close posse of fellow man-boy friends. But as he nears his 30th birthday, he and his girlfriend Jenna (a fantastic Jacinda Barret) find that after three years together, they're expecting a baby. Both want the baby, but Michael refuses to marry Jenna until she can name three couples they know who have a happy marriage. Luckily for Michael, his friends are (including Casey Affleck) are all in the crumbling stages of relationships.
Michael's generic malaise about the boringness of his life is expressed to the audience by the long, weary looks Braff gives to the camera. We've seen this before, most pointedly in Braff's 2003 Garden State (a man-boy classic). Braff's man-boy shtick may be enhanced if he added some of his small-screen comic ability (Scrubs) to the monotone men he plays on the big screen. With an unfocused stare on his false and audible exhalation, Braff, and not the future he has with Jenna, is the real bore of the film.
Screenwriter Paul Haggis (Crash) realizes that Braff's unease with paternity is not enough to move the story forward. Thus the audience gets Kim, played by Rachel Bilson (Summer Roberts of The OC). Kim is a collegiate temptress whose brightly colored wardrobe and ability to play the flute alerts Braff that she may be the antidote to the mundane life he has ahead of him. Kim is a one-note character, and Bilson is a twitch of an actress with nary a sincere or sexy bone in her body. Her delivery is perpetually stuck on the fast-paced Orange County patter of Summer.
Ultimately, Braff must choose between Jenna and Kim. The audience sees that Jenna is the clear winner, but Braff goes through the wringer of man-boy self-doubt, experimentation, and ultimately guilt, until he realizes that he can, and wants, to leave Neverland and grow up.
Jacinda Barret is the real talent in The Last Kiss because she is not a man-boy. Instead, she is a fully realized woman. She may not be able to shake her 90-pound booty to Ciara like Kim, but she can accept the complexities of love without having a quarter-life crisis. Barrett's portrayal of a woman betrayed is quite moving, and it is in this scene that the movie grows a heart.
The trouble with man-boys, and man-boy movies, is that the viewer gets dragged down in all the confusion and selfishness of the so-called protagonist while we wait for him to grow up. And sometimes movie audiences just aren't that patient.