This summer’s collection of likable coming-of-age movies is increased by this alternately charming, penetrating and rote comedy-drama from the team of Nat Faxon and Jim Rash, who among other things collaborated with Alexander Payne on the Oscar-winning screenplay for “The Descendants” but here direct too, as well as taking supporting roles in front of the camera. “The Way, Way Back” covers familiar territory, but for the most part in a pleasantly quirky fashion.

One of the period film’s more unusual aspects is that Steve Carell, usually the befuddled nice guy, plays against type as Trent, the controlling boyfriend of single mom Pam (Toni Collette). Their relationship is tested when they go off for the summer to Trent’s beachfront house on the Atlantic coast south of Boston, taking along his daughter Steph (Zoe Levin) and her son Duncan (Liam James). The focus is on the fourteen-year old boy, whom Trent treats with casual condescension, but who finds an unlikely friend in Owen (Sam Rockwell), a wild and crazy guy who runs a local water park and not only gives the kid a job there but encourages him to come out of his shell. By August Duncan’s grown up, and his mother has come to see Trent for what he is.

“The Way, Way Back”—a title that refers to the seat in the rear of Trent’s station wagon, where Duncan’s forced to sit during the drive to the coast—has an arc without many surprises, but though the destination is pretty much preordained, the journey there is largely enjoyable, thanks to some sharp writing and a winning cast. As Duncan—the linchpin of the script—James could hardly be called charismatic, but his understated approach pays dividends when the character’s reserve begins to melt away and he begins to enjoy himself—and become angry over his mother’s mistreatment by Trent. Carell is convincingly odious, especially when he teams up with an unpleasant “swinging” couple named Kip and Joan (Rob Corddry and Amanda Peet). And although you might want to slap Collette’s Pam for her obtuseness in not immediately seeing Trent for the cad he obviously is, the actress uses subtle gestures to suggest the character’s gradual, pained recognition, while Allison Janney comes close to stealing every scene she’s in as Trent’s garrulous neighbor. River Alexander is a geeky charmer as her put-upon son and AnnaSophia Robb sweetness itself as his older sister, who befriends Duncan while Trent’s daughter Stephanie (Zoe Levin) enjoys humiliating him.

But most of the movie’s pizzazz comes from the folks at the water park, especially Rockwell, who’s obviously taken a page from Bill Murray’s “Meatballs” playbook to make Owen a goofy Peter Pan type whose lackadaisical exterior conceals a warm heart. Maya Rudolph brings great comic exasperation to his put-upon assistant, while Faxon and Rash lend their expert timing to Lewis and Roddy, the former the straitlaced, put-upon souvenir-shop clerk and the latter the gregarious overseer of the park’s water slide and teaches Duncan the lascivious tricks of his trade.

Like “The Kings of Summer,” the other genial coming-of-age comedy-drama in theatres at the moment, “The Way, Way Back” is a modestly-budgeted independent production. But John Bailey’s cinematography takes advantage of the locations in Marshfield, Massachusetts, and all the other technical credits are fine. And the score—combining original music by Bob Simonsen and a potpourri of songs supervised by Linda Cohen—adds mood and emotional color to the proceedings.

After you’ve gorged yourself on the studio blockbusters, here’s an agreeable, insightful if uneven smaller film that can serve as a tasty palate cleanser. Give it a try.