On the one hand this looks kind of funny. On the other, these people are all playing themselves. Jonah Hill is playing that awkward, weird, fat kid while John C. Reilly is playing that border-line retarded character he's been knocking out in his last several films. Catherine Keener is playing that bitchy ex-wife with the big laugh, yeah, the same one from 'The Soloist'.
But at least it isn't talking chipmunks animated around Earl and the sexy Zachary Levi. At least there's that.
The low-down is thus: Reilly is what appears to be socially awkward and soon to be divorced from his wife. He meets Tomei and they start to date. She's perfect but she has a grown son (Hill) who hates Reilly. It kind of sounds like 'Stepbrothers' sans Will Ferrell and with a son instead of a stepbrother.