Very well acted, albeit formulaic, coming-of-age tale.
Our hero is 14-year-old Duncan (Liam James) who is being schlepped out to spend the summer with his mom (Toni Collette) and her new boyfriend (Steve Carell) at his beach house. The would-be stopdad is an obnoxious schmuck, and Duncan is already dreading the summer. Meeting the summer neighbors doesn't much help -- there's the perpetually tipsy couple (Rob Corddry and Amanda Peet) who are there for dinner almost every night, and the loud, brassy floozy (Alison Janney) who lives next door with her pretty young daughter (AnnaSophia Robb).
And so Duncan flees to the local rundown water park, where manager Owen (Sam Rockwell), who has never quite grown up himself, takes Duncan under his wing, and the relationship between them -- surprise, surprise -- helps both to grow up a little.
Performances are excellent, and Sam Rockwell is the standout. He's been doing remarkable work for years now -- if you haven't seen Moon, go watch it, for heaven's sake -- without ever getting the recognition he deserves, in part because he's too quirky and eccentric a presence to easily fit into any of the usual leading man molds; and while the role he's given to play here is a fairly standard lovably goofy manchild, he brings more nuance and subtlety to it than the script provides.
And the rest of the cast is also strong; everyone gets a moment or two to shine. Liam James, in the lead role, more than holds his own in this group of fine actors; Toni Collette has some particularly fine moments in a campfire scene where she realizes that Carell may not be everything she'd hoped he was.
But all of that fine acting is put to the service of an awfully familiar story -- misfit kid begins to find himself when he becomes the protege of just the right misfit grownup. The movie is written and directed by Nat Faxon and Jim Rash, who wrote The Descendants; based on that movie and this one, they don't bring a lot of originality to the table, but they can tell a formulaic story better than most. (They also play small roles as members of the Water Wizz staff.)
Entertaining, and worth seeing for the strength of the cast, but familiar enough that you could easily wait to see it at home rather than rushing out to the theater.