Here’s the thing about “Friends With Benefits” director Will Gluck; he’s a director with a gift for coaxing impressive comedic performances out of his casts, but he’s also entirely too clever for his own good.

“Friends With Benefits,” much like Gluck’s previous film “Easy A,” has some legitimately funny moments. However, it got all too pleased and bogged down in mocking other movies in its genre, constantly pointing out flaws in typical romantic comedy only to become one in its final 10 minutes.

And almost every romantic comedy trope makes it into the film. The central couple, played by Justin Timberlake and Mila Kunis, cutely meets at an airport as she tries to woo him into a ridiculously swanky job at GQ. Both are newly single, and both are so frustrated with the opposite sex that they swear off relationships forever (in several repetitive and needlessly expository scenes where they list off their neuroses). They decide to enter into a sex-only relationship, keeping their emotions separated from their physical activity, but for reasons dictated by plot and the gods of romantic comedy lore, that obviously doesn’t work out.

The entire film is built around Timberlake and Kunis, and the two prove to be a winning combination. They give lively, charming performances, and their chemistry is tangible enough to drive the film toward its inevitable conclusion. Not to mention they’re both hilarious.

In fact, most of “Friends With Benefits” is honestly funny. Timberlake and Kunis surprise with their sharp delivery, and Woody Harrelson is a comedic force of nature as a flamboyant sports writer. Gluck has an undeniable touch for establishing a quick, easy comedic rhythm within a scene and does his best to pack the film with jokes that work more often than not.

It’s because the film is so funny so often that it’s actually enjoyable for most of its runtime, even as its cast goes through the motions of a cliche narrative. Unfortunately, its last 10 minutes segue all the way into romantic comedy territory, complete with the big romantic gestures and forced pop soundtrack that were mocked earlier in the film. While Gluck unsuccessfully tries to make the drama work in a sort of ironic way, Timberlake and Kunis are convincing enough as these characters that even the substandard final moments aren’t excruciating.

“Friends With Benefits” works for a lot of reasons, but the biggest are by far the leading actors. They’re likable, charismatic and show off unexpected comedic chops here. For fans of romantic comedies, prepare to be pleasantly surprised. For guys who find themselves dragged to romantic comedies, you could certainly do worse than “Friends With Benefits.”