Watching two old geezers putter around Central Park may not be most people's idea of engaging cinema, but I'm Not Rappaport makes this kind of septuagenarian buddy dramedy tolerable enough. Walter Matthau and Ossie Davis, both pushing 80, prove they still have sharp command of dialogue and humor, so their lengthy conversations don't induce seat squirming as fast as they might in lesser hands. Matthau in particular is fun as an accomplished and compulsive liar, who fragments together plausible personas without missing a beat. Still, Herb Gardner's adaptation and direction of his own play can't overcome the narrow appeal of its subject matter. It's a great showcase for actors usually relegated to supporting roles (or sent out to pasture) by their age, but that's not much of a selling point beyond their immediate families or fan clubs. Matthau's Marxist meddling with a variety of secondary characters feels stagy, and his scenes with his estranged daughter (Amy Irving) are flat and superfluous. Gardner does capture some of the invigorating life force of Central Park, but 135 minutes of it is too much. A two-person character study should clock in at well under two hours, especially when the characters travel in such a slim radius. I'm Not Rappaport is like one of those long, rambling stories told by a grandfather in dire need of attention, unaware his polite audience is bored to tears.