Christopher Guest and Eugene Levy create a skeleton of a plot to hang the improv scenes on. I imagine the movie-within-a-movie "Home For Purim" sounded funnier than the result onscreen: A Tennesee Williams-style southern melodrama, but featuring a Jewish family reuniting for Purim. Plenty of people in my audience were cracking up at the Jewish jokes, but I was only mildly amused. Rachael Harris showed a lot of potential as the lesbian girlfriend Mary Pat Hooligan, but her character just peters out.
Several scenes were included which were necessary to advance the plot, but were not funny. For example, Parker Posey and Christopher Moynihan are a Reese and Ryan-style couple. When she is rumoured for an Oscar nomination, she senses his jealousy, and they argue over it, but the scene of them arguing is not funny- I imagine the improv juices weren't flowing?
Perhaps the Hollywood premise is worn out, or the magic just wasn't there, but FYC just didn't spark. (Kendall Square Cinema)