As sequels go, Analyze That is not the best one ever made, but it’s not the worst either. Billy Crystal and Robert De Niro have so much fun playing psychiatrist and mobster-patient again that it’s highly contagious. Despite a more unbelievable plot this time, some parts of the movie are even funnier than those humorous therapy scenes in Analyze This. Watching De Niro warble musical numbers from "West Side Story" emerges as one of the film’s comic highlights. When he sings "I Feel Pretty," it brought down the house at the screening I attended.

Paul Vitti (De Niro) pretends to be mentally ill in order to get out of prison and back in Dr. Ben Sobel’s (Crystal) care. Someone in prison tried to kill him. Naturally, he wants to find out who and why. And a befuddled Sobel becomes more involved than he should in Vitti’s plans while, at the same time, trying to treat the former mob boss and help him find a normal job. After a series of disastrous, and hilarious, placements, Vitti ends up as a consultant on a television crime show called "Little Caesar." Dr. Sobel soon discovers Vitti plotting with his old associates and wonders if all his efforts have been in vain.

After all, Sobel knows he’s not at his best because he’s grieving over the recent death of his father. "It’s a process," he tells anyone who will listen. He certainly doesn’t want Vitti in his custody at this point in time. But he has no choice. Government officials make it an order. Crystal and De Niro project a wonderful give-and-take as their characters interact with each other in this situation. Early on, they share an extremely funny scene in which the psychiatrist does outrageous things to Vitti to discover if he's faking a catatonic state. Crystal pinches DeNiro’s face, barks like a dog right into his ear, and sticks a hypodermic needle into his leg. De Niro doesn’t even blink, except in the outtakes. What a trouper! (But don’t try this at home.)

Why are these two characters such a hit with movie fans? Referring to Analyze This, Billy Crystal says, "People would stop me on the street and quote lines from the movie. ‘You . . . you’re good. You’ve got a gift,’ they’d say, imitating Bob. It really tickled me."

Producer Jane Rosenthal has her own theory. "I think audiences just loved seeing Robert De Niro taking his scary screen persona and having fun with it," she offers. Crystal adds, "People just love to see De Niro abusing me."

Whatever the reason for the success of Crystal and De Niro as Paul Vitti and Ben Sobel, Analyze This taps into that same formula and provides the kind of "laugh therapy" I need from movie comedies -- offbeat humor, amusing characters, and a happy ending. After seeing Analyze That, I feel better already.

(Released by Warner Bros. and rated "R" for language and some sexual content.)