Top Five 2.5 stars Directed by Chris Rock Starring Chris Rock, Rosario Dawson, Gabrielle Union Rated R

Chris Rock, the writer, director and star of "Top Five," can take all credit and blame for delivering one of the most maddening comedies of the year. One minute it's a major letdown, the next minute a joy to watch.

Rock plays Andre Allen, a popular stand-up comic who insists that he is now a serious actor. Allen's violent new drama about a Haitian revolution, "Uprize" is playing to empty theaters, while his reality-star fiancée, Erica (Gabrielle Union), is rearranging seats for their televised wedding. Enter Chelsea Brown, a New York Times reporter played by a street-smart Rosario Dawson. As the two ramble around New York City, their ongoing argument turns into mutual therapy (both are recovering alcoholics) and then into mutual attraction.

At its best, "Top Five" makes a case for Rock as the best American director of the French New Wave. The movie bubbles with the joie de vivre of a Francois Truffaut movie. The best scenes feel unscripted: Rock just riffing, Dawson needling him, and supporting players like Kevin Hart adding to the fun. Propelled by Questlove's rhythmic score, "Top Five" often sparkles with a jazzy, metropolitan energy.

At its worst, "Top Five" resorts to raunchy, pandering humor, most notably a gross-out routine involving Cedric the Entertainer and two prostitutes, and a gay joke that comes out of nowhere and goes on forever. The more closely scripted scenes feel derivative, clunky and false.