Ah, the Broadway musical. A sitting-duck target for some pretty unmerciful snubbing (or just plain ignoring) by the magistral proponents of intellectualism and high art. And yet, for the critic who can't resist a good show or the damnably hummable tunes of a Rodgers or a Lloyd Webber, a really professionally staged musical is often a source of lively, if somewhat guilty, entertainment. So it is with the lavish production of the Kern-Hammerstein classic "Showboat" currently playing at the Wang Center through August 13.

The sheer extravagance of the production is bound to win over most, if not all, viewers. The multilayered set is a marvel; with a few turns, the Cotton Blossom shifts between views of the cabin windows, the boat's prow and box office, a kitchen pantry, the interior theater and the upper deck where the young lovers, Gaylord Ravenal and Magnolia Hawks, hold their trysts. The second act is set in turn-of-the-century Chicago, the centerpiece being the Palmer House Hotel. But here, too, the set undergoes a series of eye-popping transformations, conjuring up scenes as divergent as the gate of a convent and the glitzy interior of the Trocadero Night Club before flipping back to Main Street. The passing of time from 1889 to 1921 is ingeniously marked by the use of the Palmer Hotel's revolving door, the headlines at a newsstand and the changing attire and manners of the Chicago denizens who pass through the streets. One might say, with perfect justification, that the set is the real star of the show, though it's matched by solid costume designs and spirited, engaging choreography.

The spectacular visuals almost succeed in masking the inherent weaknesses of the play. Almost, but not quite. Dating from 1927, "Show-boat" is really a nostalgia piece, and as such it has its problems. The plot is hopelessly old-fashioned, with an anticlimactic "happy ending" that seems both clumsy and artificial. The characters remain for the most part one-dimensional; the most interesting ones simply sink out of sight, into oblivion or irrelevance. The love story never really works; even the early scenes between Ravenal and Magnolia have an unavoidably mechanical feel, and the romantic duet that concludes Act One is pretty insipid stuff next to "West Side Story" or even "The Sound of Music."

More irritating is the sidelining of the black characters, "Ol' Man River" notwithstanding. One especially grating moment involves a little exchange between Cap'n Andy, the proprietor of the Cotton Blossom, and the wise slave Queenie in which the latter, in response to Andy's grumbling that the balcony seats aren't selling, asks him "What about colored folks?" and launches into a ballyhoo aimed exclusively at said "colored folks." However, both Gretha Boston, who won a Tony award for her performance as Queenie, and Andre Solomon-Glover as Queenie's husband Joe, establish considerable presence that prevents their characters from being altogether marginalized. Toward this end as well, Joe's (and the show's) signature song, "Ol' Man River," is repeated several times throughout the show after its far-too-early first appearance--a nice idea, even though the recurrence of the song sometimes seems slightly out of place. Solomon-Glover is sufficiently imposing as Joe, even though he doesn't quite fill the enormous shoes left by Paul Robeson.

Amid its shortcomings, the script of "Showboat" does have its moments. A particularly witty scene--in fact, the funniest in the entire show--presents a satirical parody of "showboat" theater, the kind of absurd melodrama that makes the framing drama look great in comparison, and reaches its pinnacle of hilarity with Cap'n Andy's spirited one-man enactment of the denouement and the wonderful punchline: "Curtain! No refunds." And the irresistible swing of "Can't Help Lovin' Dat Man" will have you humming or whistling it before you exit the theater. No wonder that song, along with "Ol' Man River," keeps cropping up. This is assuredly a production that makes the most of the musical's best points.

Tom Bosley (a TV veteran best known for his roles in "Happy Days" and "Murder, She Wrote") makes a fine Cap'n Andy, jovial and kindly but with unexpected edge. The rest of the cast are generally quite good in their stock roles. Sarah Pfisterer as Magnolia demonstrates some impressive vocal chops and manages to convey the girl's radiant innocence winsomely, as well as her later, more subdued dignity as an abandoned wife. Real-life husband-wife team Kirby and Beverly Ward almost steal the show as the husband-wife comic team of Frank and Ellie who leave the show-boat for a gig in the Trocadero. And Elizabeth Mary O'Neill does steal the show, if only briefly, as Magnolia's daughter Kim: her Charleston, near the very end of the show, is a terrific eyeful with a lot of pizazz--the best-choreographed and quite possibly the best scene of the entire show.

But the human performers, fine as they are, simply can't compare to the $10 million worth of eye candy that surrounds them. And perhaps it's just as well: "Showboat" is just what its name signifies, a spectacle that's meant to dazzle and entertain--and collect admission. On these terms, this "Showboat" scores a resounding success.