Herb Gardner could have subtitled "I'm Not Rappaport" something like "Life in Central Park."

Certainly, Central Park is unique among American gathering places, and anyone who has ever taken a stroll there knows the kind of off-center personalities that populate the place. In one sense, Gardner's Tony Award-winning play (which he adapted and directed for this film) is a picture-postcard observation of some of the more colorful folk who practically live there.

The main reason to see "I'm Not Rappaport," however, is the chemistry between Walter Matthau and Ossie Davis, who play a pair of oldsters who argue on a park bench with such passion that you'd think their conversations acted as some sort of elixir.

Matthau is Nat Moyer, essentially the lead character, an idealistic self-motivated activist who makes a nuisance of himself attacking institutions that he feels prey on the elderly. This drives his daughter (Amy Irving, in the best of the supporting performances) to distraction, and she threatens to have him declared incompetent.

Davis is Midge Carter, who is in danger of losing his job in the boiler room of an equally aging hotel. As someone who has avoided confrontation all his life, he is unable to stand up to those who threaten to put him out on the street, and this is demonstrated in his inability to stand up to Nat, even when the latter is regaling him with outrageous tales of his exploits in younger days.

Gardner has kept what is essentially a three-act play intact — although it has been "opened up" with location shooting — building the action around three meetings between Nat and Midge. And Gardner's prose is wonderful in the thoughtful and sometimes hilarious speeches delivered by Matthau and Davis.

The biggest flaw is in allowing the movie to go on too long — 2 hours and 15 minutes to be precise. This seriously hampers the pacing, and it sags far too often. Trimming might have made the entire production soar in a way that it currently does not.

But there is much to enjoy, and most of it comes from Matthau and Davis. While Matthau's career has soared in recent years (especially in tandem with Jack Lemmon), Davis has not been seen quite as much. But, as this film attests, he is every bit as vibrant as his on-screen partner, and it would be wonderful to see more of him.

"I'm Not Rappaport" is rated PG-13 for violence (Davis is attacked by a youth in the park), some profanity and vulgarity and marijuana smoking.