"Words, words, words," protests Eliza Doolittle in "My Fair Lady," "is that all you blighters can do?"

It's a funny preemptive strike by lyricist Alan Jay Lerner, so many of whose words are taken directly from the wonderfully wordy George Bernard Shaw, whose comedy of transformation, "Pygmalion," is the origin of this magnificent musical. But Lerner's fears and Eliza's frustration to the contrary, words are its glory, joining it with "Kiss Me Kate" and "A Little Night Music" as literate musicals that are, in effect, good enough to stand alone as plays.

Add Frederick Lowe's richly melodic score, and "My Fair Lady" scales the heights. From pop ballad to music hall romp, from musical monologue to ethnic pastiche, the score is a marvel of variety, as musically witty as Shaw's and Lerner's words with which it is so intertwined.

This lavishly literate pleasure arrived at the Benedum Tuesday in a national tour based on a hit English production. Pittsburgh is its first stop, and though there were a few opening night glitches -- an occasional imbalance between singers and orchestra is the only one that bothered me -- it does the show proud.

One of its chief achievements is the choreography of the ever-inventive Matthew Bourne (re-staged by Fergus Logan), whose signature number is a percussive, audience-rousing version of "With a Little Bit of Luck" that rises to a "Stomp"-like crescendo of ashcan lids. The other big, showy number is a very fluid "Get Me to the Church on Time," which pours Alfred Doolittle through the London streets and into a whole music hall extravaganza.

You also see Bourne's good work in the prologue, where he establishes the class divisions that huddle under the portico in a rainy Covent Garden, and in more measured movements elsewhere, from the haughty comedy of the "Ascot Gavotte" to the private joy of "The Rain in Spain."

But in truth, "My Fair Lady" isn't a choreographer's show. It belongs mainly to the actors, and original director Trevor Nunn and tour director Shaun Kerrison have done good work, insisting that Eliza and Prof. Higgins play truthfully -- perhaps even to a fault.

It all hinges on Higgins. Christopher Cazenove plays his infuriating self-centered iconoclasm for all its worth, relishing every delicious word. He also makes clear Higgins' unthinking intellectual imperialism, determined to educate up to a god-given standard, unwilling to credit any values other than his own. And his Higgins never gives any hint of romantic sentiment.

This is all as Shaw intended, but the musical also wants to hint at something more sympathetic than the play, and Cazenove refuses to do so. His burly, egocentric authority is complete. And given his middle-aged stolidity, he lacks Higgins' boyishness, the source of his charm.

He is certainly a formidable opponent for Eliza, but Lisa O'Hare is his match. She is a convincing waif with an iron will who polishes up into an Audrey Hepburn-like beauty, but with a more believable common touch. This makes her late return to her old haunts in Covent Garden intensely moving.

But what this magnificent young woman is doing returning finally to this Higgins, I cannot imagine. I think Shaw would agree -- and this production seems to, as well, defusing that final wishful moment with shared laughter that poses more questions than it answers.

Providing warmth and glamour as Higgins' mother is Sally Ann Howes, a link to the original "My Fair Lady" of a half-century back. Justin Bohon is a suitably jejune Freddy, and Walter Charles' Col. Pickering, although initially pallid, grows into an eccentric comic presence.

Tim Jerome's Alfred Doolittle, the philosophic dustman, is a torrent of music hall skills. But to director Nunn's credit, he isn't just cute. There's a real Dickensian darkness in the London nighttown where he carouses -- you can see prostitutes plying their trade on the fringes -- and there's desperation that is more than just comic in Doolittle's debauch.

Anthony Ward's sets have the simplicity of structure that touring demands, being based on an all-purpose arcade, but they provide plenty of color. I especially like Higgins' study, with its bookshelves crammed higgledy-piggledy with the materials of a voracious but undisciplined mind. And the famous statue of Eros in Piccadilly Circus makes an intriguing background for Doolittle's carousing.

The producers have not stinted on the supporting ensemble, which is large and active. And Ward's costumes are as lavish as one could wish. Gone is the black-and-white Cecil Beaton design for Ascot, but Ward's aristocratically dark and glittering garb is very elegant and more appropriately intimidating.

You can't expect a musical -- even one as long as this -- to plumb all the serious issues of class and gender, economics and morality, implicit in the story. As Eliza trenchantly observes, Higgins has turned her into a matrimonially saleable product, but that's a social problem beyond a play to solve. (Nunn cleverly refers to it by invoking a woman's suffrage protest in passing.)

Even Shaw found himself distracted from all that by the fun of his comedy. But the issues are still there, which gives "My Fair Lady" an impact beyond that of entertainment. Call it a version of "Cinderella" for grown-ups, but one in which the Prince is just the figment of one dance and real life is more interestingly complex.

O'Hare is a very satisfying ugly duckling princess and Cazenove, an imperious magician (although who gave Eliza her dancing lessons?). As to what their future lives might possibly be, who can tell?