Reilly plays John (Mumblecore-type naming strategy at work), who's an "editor" who doesn't do much. All he can muster is that he "has a big DVD collection." At the start he's got no one, "left" by the beautiful Catherine Keener (who has something off in her performance), left "scratching his jocular." Jamie (Keener) forces him to go to a party, and even not by seeing the film's trailer you should know that this is going to work some sort of results for John. John makes a complete ass of himself (acting a little like when he drank "sweet berry wine") by getting drunker and drunker on Red Bull and Vodkas. His idiotic antics catch the eye of Molly (the equally attractive Marisa Tomei). John thinks things are looking up and that he's finally gotten himself into a good relationship.
Of course not. He has instead gotten himself into a shattering, problematic situation. He follows Molly home, falls asleep in his car, "semi-stalks" her by going up to her house, and he finds someone at the door: Cyrus (Jonah Hill), her son, who's a techno musician with a thing for mashing up music and "landscapes." Seems like an innocuous guy at first, although to John it's a little bit of a blow to end up with a lady with a "Momma's boy" for a son. It steadily gets worse, however, with Cyrus desperately and manipulatively wanting to keep his mother all to himself and John not wanting to let go of something finally nice in his life. It starts with small incidents, but then it escalates a little more into "war."
There are some interesting ideas that a viewer like me could think of that are ignored by Jay and Mark Duplass to keep the film from veering from "uncomfortable" (as critics have said) to something worse, such as the true depths of Cyrus and Molly's relationship. Also some that are perhaps simply too deep, such as how Jamie feels about John (respect or not?), which is really another motherly relationship that recalls the adults-as-"kids" reversals that critics have brought up in dealing with "The Kids Are All Right."
None of this is given thought. It would diverge even further from what it already has diverged from, which is a "comedy" (as people said) with a touch of "uneasiness." It is (as people said) "mildly funny," in how Reilly is (like Nick Davis said) and how he looks when he's perplexed. Still, (as said before) it doesn't get much beyond that, although being well-cast, not being well acted (except for Hill, who does well with his two-faced mix of Cyrus the Great and amiable and tender).
The film is strung together with jaunty sequences with forgettable music that show very little effort put in by the Duplass Brothers, and finds itself plodding through an ending (About Face! But NOT QUITE!) that made me enjoy the film even less than I had before. It sometimes works itself up to being a little enjoyable, but not too much. Not much of it is entirely satisfying (just being unpleasant, or, when it's a little more upbeat, screwing things up with dumb technique such as audio that doesn't match video, or ending with a cheesy, totally Mumblecore ending), and that's no good sign. Aside from some "merits," this wasn't a very "appreciate"-able film (I'm struggling with how to say that, just like the lady introducing "Restrepo" at the screening I went to, and I have settled on her word choice). C