The musical adaptation of Adrienne Shelly’s 2007 indie beaut Waitress, with songs by Sara Bareilles and Tony-winner Jessie Mueller (Beautiful: The Carole King Musical) in the title role, opened Thursday in its Broadway tryout at the American Repertory Theater in Cambridge, MA. Slated to begin performances in March 2016 at the Nederlander-owned  Brooks Atkinson Theatre, the show is staged by Diane Paulus (Finding Neverland, Pippin). Advance word has been good, making the musical one of the most eagerly anticipated of the new season. Beantown critics were mostly upbeat on the show, and more than positive on Mueller’s performance as an unhappily married pregnant waitress with a gift for piecraft.

“Adhering closely to the film but replacing its droll interspersing of offbeat pop and classical bursts with an original score, Waitress is the singing, dancing equivalent of chick lit,” wrote Carolyn Clay, writing for public radio station WBUR. “Smartly then, Paulus has matched it to a mostly female creative team, the cleverest choice being that of Grammy-nominated singer-songwriter Sara Bareilles as composer/lyricist. Bareilles has never before undertaken a musical, but her pulsing, piano-driven tunes and sincere, ringing ballads both carry the story and set the now quirky, now aching mood. Waitress(One cavil: There are too many sentimental numbers in the second act)…Most importantly, the songs keep things moving as fast as Scott Pask’s ingenious scenery, which whisks in and out of the principle diner locale against a backdrop of highway and power lines stretching into the distance. The fast pace is probably for the best, since the story is essentially one of a miserably married woman whose unlikely affair with her gynecologist hoists her firmly enough into the stirrups that she can ride her own life into the sunset. I mean, is that every horrible husband’s nightmare, or what?…The book, by playwright-screenwriter-film director Jessie Nelson, borrows much dialogue from the film but amps up the sex and zingers…Paulus’s A.R.T. production, backed by a seven-person combo led from the piano by Nadia DiGiallonardo, is as sharp as the pies are sweet.”

In the Boston Globe, Joel Brown said that, “Jessie Mueller’s terrific performance in the new musical Waitress at the American Repertory Theater makes one hope she’ll still be starring when the show, helmed by ART artistic director Diane Paulus, debuts on Broadway next spring. The actress brings a weary gravity to the title role of the ‘desperately sad’ Jenna, along with a luminous singing voice… WaitressEspecially in the second act, Mueller elevates an entertaining show that faithfully follows the 2007 movie that starred Keri Russell, including some bits that are only sitcom deep…Sara Bareilles’s songs give Jenna and one or two other characters a chance to explore their feelings, and they’re best when they stay close to her normal singer-songwriter mode. Jenna’s second-act solo number, ‘She Used to Be Mine,’ is the night’s showstopper.”

Frank Rizzo, in Deadline’s sister publication Variety, summed it up thus: “[W]hile this feminist fairy tale of a show, in which singer-songwriter Sara Bareilles makes an impressive legit bow as a composer, is quite delicious at times, it still needs more work — especially in the second act — before it’s a recipe for success.”

The show runs in Cambridge until the end of September.