Broadway has just re-entered that “Caroline, or Change” zone. The controversial show this season is Craig Lucas and Adam Guettel‘s inventive “The Light in the Piazza,” which opened April 18 at Lincoln Center Theater to mixed reviews.

While almost every critic found aspects of the show to admire, once again, a small but influential group of Gotham reviewers has greeted with skepticism a serious work that pushes musical theater in a new direction.

“It’s part of a theatrical tradition. ‘Twas always thus with serious musicals,” says LCT’s artistic director, Andre Bishop. There have been a few exceptions, he points out. Back in the 1940s, Rodgers & Hammerstein’s “Carousel” and “South Pacific” were universally embraced by the critical establishment. Since then, it has been rough sledding.

Here’s a quick tour of New York’s notoriously conservative critical tradition:

Walter Kerr (Herald Tribune) on “West Side Story,” 1957: “It is, apart from the spine-tingling velocity of the dancers, almost never emotionally affecting.”

Martin Gottfried (Women’s Wear Daily) on “Cabaret,” 1966: “The story is uninteresting, unamusing and time-consuming.”

Clive Barnes (New York Times) on “Chicago,” 1975: “One might be tempted to say that never in the history of the Broadway theater has so much been done by so many for so few final results.”

In more recent times, money reviews have been reserved for lighter pastiche shows such as “The Producers,” “Hairspray” and “Monty Python’s Spamalot,” which essentially refashion familiar melodies. Guettel’s music, on the other hand, challenges expectations, and it may take the Nonesuch recording (due out mid-May) for his work to be fully appreciated.

“It was with the revivals and repeated hearings (of records) that Stephen Sondheim‘s shows became legendary,” says Bishop.

Likewise, the “Caroline” CD had much to do with that show’s critical reversal earlier this year in L.A. and San Francisco, where it was greeted with raves.

Dori Berinstein‘s new docu, “SHOW Business,” which premiered last week at the Tribeca Film Festival, features a round-table of crix, who, for the most part, felt “Caroline” broke no new ground theatrically. Would they say the same of “Piazza”?

Without the glue of recitative, Guettel offers nothing but big, florid arias showcased between long stretches of Lucas’ spoken dialogue. This is a major departure from such so-called operatic Broadway fare as “Candide,” “The Most Happy Fella,” “West Side Story” and “Sweeney Todd.” Although often performed in opera houses, those shows are larded with standard Broadway comedy numbers like “I Am Easily Assimilated,” “Oh, My Feet,” “Officer Krupke” and “A Little Priest.”

Arias like Guettel’s are more likely to be strung together with recitative, and it is telling that he has eschewed this approach. Perhaps he took a cue from Sondheim, who has dismissed recitative as the “chocolate sauce poured over everything.”

Guettel is a bit kinder in his assessment of the sung-through show. As he explains it, the lyricism of song and the naturalism of the spoken word are “always fighting, and recitative is a way to deal with that tension.” In “Piazza,” he accentuates the leap between spoken word and song. Apparently, critics have found this stylistic flourish either exhilarating or jarring.

Regarding the mixed reviews given the show, criticism has been leveled at Guettel and Lucas’ choice to put some scenes and arias in Italian to tell the story of an American mother and her daughter in Florence. Guettel responds: “I’m not discouraged, because I know it works. There’s a lot of energy in that language barrier. We wanted the audience to be in the same position as the Americans. ”

In a couple of those arias, the Italian and English lyrics give way to a la-la-la vocalise. “When language breaks down, when you cannot go further with language,” says Guettel, “then music becomes a metaphor for a universal language.”

Guettel writes in the tradition of Benjamin Britten, and while “Piazza” isn’t his “Peter Grimes” or “Billy Budd,” it seems likely to comfortably take its place alongside “Turn of the Screw” in the repertory of the world’s more intimate opera houses. Intriguingly, it will be performed with surtitles, as almost all English operas are in the United States.

“That’s all right,” says the lyricist-composer. “But on this first go-around, we wanted to use the Italian as part of the storytelling.”

It’s just as well. With surtitles overhead at the Vivian Beaumont, some crix might have added the word “pretentious” to their reprimands.

Not that “The Light in the Piazza” is without its early fans. “We have the gamut of critical reaction,” says Bishop. Good omen: A minor crix org, the Outer Critics Circle, last week gave the show 11 award noms.