Film-class instructors trying to explain why a movie needs a strong script have the perfect example in the new (sort-of) sequel, "Blue in the Face."

In fact, the contrast between this film and its antecedent, "Smoke," is quite remarkable.

Where "Smoke" was designed as a strong story-telling vehicle, "Blue in the Face" is simply a lark. Where "Smoke' was a tightly scripted, funny and touching series of interwoven vignettes about the human condition, "Blue in the Face" is merely a series of disconnected, improvised comedy skits.

Director Wayne Wang and writer Paul Auster simply extended their "Smoke" shoot by a week and gave the actors vague situations, allowing them to adlib dialogue for 10-minute scenes that would be shot without interruption. Or, in other words, until the performers were "Blue in the Face," which explains the film's title.

Described in press materials as an all-star experimental film, "Blue in the Face" does have its amusing moments, but it also has way too many that fall flat or go nowhere.

Those who go in expecting anything as fulfilling as "Smoke" will be sorely disappointed.

The location is the Brooklyn Cigar Co. , and the central character is manager Auggie Wren (Harvey Kietel, who is excellent and once again the film's acting anchor). He offers a nominal narration and acts as the spiritual center — or, perhaps, referee — to a parade of New York eccentrics who wander into or pass by the shop.

Among them are a number of celebrity cameos. The funniest are droll monologues by rock-star Lou Reed and cult-filmmaker Jim Jarmusch, along with a singing telegram delivered by Madonna. Strangest are Michael J. Fox as a vulgar pollster and Lily Tomlin as a homeless man (no, that's not a typo — she plays a man). And least tolerable is Roseanne, as the shrill (what else?) wife of the smoke-shop owner (Victor Argo).

The best skit, however, is the hilarious opening sequence, an encounter between Auggie, a young purse-snatcher (Sharif Rashed) and an innocent passer-by (Mira Sorvino, who also co-stars in "Mighty Aphrodite").

The ghost of Jackie Robinson also makes an appearance, convincing the owner of the Brooklyn Cigar Co. not to sell out and allow the long-time smoke shop to become a health-food store, which provides about all the plot there is.

The recommendation here, and it's a modest one, is strictly for fans of "Smoke." If you didn't see that film, this one will mean nothing to you. And even if you did, it won't mean much.

"Blue in the Face" is rated R for some violence, a fair amount of profanity and vulgarity and some female nudity.