Upstairs at Chasen's, in the Jockey Club bar where men can smoke cigars and eat chili, Jack Nicholson and James L. Brooks are doing both. Seated in an ornately brocaded booth in the late afternoon light that will soon be gone, the two Hollywood long-ball hitters lob compliments at each other through the pungent haze, jog back through the mists of fable, laugh, kid, ponder and take stock of their unordinary lives as a reporter tosses questions on the table between them. They have just finished the last arduous tinkering with "As Good as It Gets," their first movie together since "Broadcast News" in 1987 and they are not waiting any longer to exhale. (The movie opened Tuesday.)

"For instance," says Nicholson, who is wearing a smart wool sport jacket with knit polo shirt underneath, "after the first preview, he calls me--this is typical Jim stuff--and I say, 'OK, how did it go, buddy?' He says, 'Well, all right. We got great scores, you're higher than Gump and they just laughed and laughed and laughed. And I said, 'God, man, that's great.' And he says, 'It's too funny.' I said, 'Jim, it's a comedy.' He says, 'No, they're laughing too much.' And I thought, 'This is who I'm workin' with.' "

"As Good as It Gets" is an unusual comedy in which Nicholson is cast as a nasty, selfish, obsessive-compulsive Manhattan loner (a romance novelist, as it happens) whose flamboyant insults aimed at anyone in his path are nonetheless amusing--except to those receiving them. Melvin, the writer, is drawn out of his anti-social cocoon by a slow-building interest in the only waitress in town (Helen Hunt) who will put up with his crazy culinary demands and by a most unlikely alliance with a gay artist neighbor (Greg Kinnear) who needs a helping hand after he is nearly beaten to death by a gang of young thieves. The neighbor has a dog that needs walking. Melvin hates dogs and hates gays.