''Little Shop of Horrors'' has always been an odd musical. It's not just that it's based on a 1960 Roger Corman horror flick, or that it revolves around a nebbishy flower-shop worker named Seymour, his tawdry but good-hearted girl, Audrey, and the man-eating plant that eventually devours them both. No, the strangest aspect of ''Little Shop'' is that just barely beneath the surface beats a sentimental heart. It never condescends to its characters or reduces them to cartoons; it has the goofy spirit of camp, but not its chilly superiority.
Perhaps that combination accounts for the show's success: After its 1982 debut, ''Little Shop'' enjoyed a 2,209-performance run Off Broadway before spawning a 1986 feature film and countless high school productions. Now it has finally arrived, via this circuitous path, on Broadway -- and if some of its subtler charms have been lost along the way, it's still enormously entertaining.
Chief among the show's appeals are its songs by Alan Menken and the late Howard Ashman -- the duo responsible for the music in Disney's ''The Little Mermaid,'' ''Beauty and the Beast,'' and ''Aladdin'' -- which marry intricate wordplay to the pop sound of the early 1960s. The show owes such a debt to the girl-group sound that its Greek chorus of backup singers bear the names Crystal, Chiffon, and Ronnette. Remarkably, the producers have found a trio of singers who actually live up to those names, and their Seymour, Hunter Foster (''Urinetown''), deftly balances his performance on the thin line between the real and the surreal.
In their Audrey they have not been quite so lucky. Kerry Butler (''Hairspray'''s Penny Pingleton) has the unenviable task of filling the shoes of Ellen Greene, who played the role Off Broadway and later on screen. Greene turned Audrey into a figure of genuine pathos -- a fragile, helium-voiced airhead who could turn on a dime and sing with a ferocious, aching intensity. When Greene delivered a ballad about her desire to move to a suburban tract home with ''a fence of real chain-link,'' it may have been a song about longing for a parody of Cold War-era domesticity, but she made it into a song about longing, period. Butler employs many of the same mannerisms and inflections as Greene, but she doesn't quite pull off the same trick -- we get the comedy of Audrey, but not the poignancy that helps give the show its emotional undertow.
Butler isn't helped by the fact that ''Little Shop'' may be better suited to the intimate confines of an Off Broadway house than to a big Broadway theater. It was designed to be done small and on the cheap -- small cast, no splashy production numbers, and a minimum of set changes. While director Jerry Zaks has wisely decided not to convert the show into a Broadway spectacle, there are times when the 12-person cast seems in danger of being swallowed by Scott Pask's massive set.
But if some of the show's nuances get lost, what remains are insanely clever songs like ''Downtown'' (a wicked takeoff on the Crystals' sunny ''Uptown'') and big, broad moments, of which there is no shortage. This is, after all, a musical with a tribute to the sadistic thrills of dentistry (rhyming ''bicuspid'' with ''maladjusted,'' no less). And it is difficult to resist any show that ends with a man-eating plant extending beyond the proscenium and menacing the audience. Consider: How many Broadway stars are willing to mingle with their public?