“Porgy and Bess” has always been a controversial piece, and it has been both claimed and rejected by the African-American community over its lifetime. The American Repertory Theater’s new rendition, directed by Diane M. Paulus ’87, faces its own additional controversy over its radical reinterpretation of the original. In converting the opera into a musical, Paulus has updated its language and reimagined a number of characters. These changes, among others, prompted Stephen Sondheim to write a critical open letter in the New York Times: “Advertise it honestly as ‘Diane Paulus’s Porgy & Bess,’” he wrote scathingly, “and to hell with the real one.” Despite the strife it has caused in the theater community, Paulus’s reinterpretation, which runs until October 2 on the Loeb Mainstage, hits many high notes. Vibrantly emotional performances by Norm Lewis (Porgy), Audra McDonald (Bess), and supporting cast coalesce effectively and the show’s technical aspects are refreshing and appropriate. However, the show’s pacing and transitions seem to have suffered in the conversion from opera to musical; the tonal oscillations between manic and tragic sometimes feel contrived.

DuBose Heyward and George and Ira Gershwin debuted “Porgy and Bess” in 1935. A tale of impoverished blacks living on “Catfish Row” in 1920s South Carolina, it is simultaneously immersed in racial controversy and lauded as the Gershwins’ magnum opus. Bess, the fast-living girlfriend of Crown (Phillip Boykin), falls in love with beggar and cripple Porgy after Crown violently murders one of Catfish Row’s inhabitants and is forced to flee. However, Crown’s eventual return and murder at the hands of Porgy, as well as Sporting Life’s (David Alan Grier) seductive siren call of hedonism and cocaine (“Happy Dust”), compel Bess to make a choice between leaving Catfish Row and staying with Porgy.

McDonald plays Bess as both a wild-eyed Happy Dust addict and a woman desperately wanting to live a “decent life.” Her voice seamlessly floats between operatic highs and bitter, grating lows, meshing well with Lewis’s Porgy (“Bess, You Is My Woman Now”) in ethereal duets. Her stage presence is packed with kinetic wrath, but also descends on occasion into a strangely vulnerable and childish attitude.

Lewis’s voice serves as the perfect complement—smooth, strong, and assured in contrast to McDonald’s sporadic trills. “I’ve Got Plenty of Nothing,” Porgy’s joyful claim that he is content with his material poverty—“got my gal, got my Lord, got my song”—highlights Lewis’s purposeful tone, along with the outstanding closing number “I’m On My Way.”

Boykin’s Crown is the brash villain of the piece, but his characterization undergoes a drastic shift from the Gershwins’ version. Originally a more menacing presence, Boykin plays Crown as a confused, impulsive addict. This interpretation conflicts uncomfortably with some of the best moments in the stage design, which features a semi-circular backdrop that is lifted asymmetrically to create the feel of a spinning hurricane. When Crown returns from hiding, the backdrop lopsidedly rises to reveal his outline in the pouring rain, prepared to take Bess away from Catfish Row; however, his confusion and immediate departure to look for bereaved soon-to-be widow Clara (Nikki Renée Daniels) dampens what could have been a more striking moment. The other technical aspects shine, as the orchestra handles the difficult score superbly, and the costuming and choreography blend naturally even though there are often a dozen people on the stage.

As comic relief, Grier’s Sporting Life and NaTasha Yvette Williams’s Mariah create the memorable “I Hate Your Strutting Style” where Mariah chases Sporting Life around the stage with a brandished knife for peddling Happy Dust. However, the upbeat interludes provided by Grief and Williams perpetuate the show’s greatest failing: its vacillating emotional timbre. The original opera is certainly filled with ups and downs. As soon as Porgy or Bess gains something, it is cruelly taken away. However, in Paulus’s rendition, the oscillation between upbeat and emotional numbers seems inappropriately abrupt. When Bess comes to pay her respects to Serena (Bryonha Maria Parham) after Crown kills her husband, Parham sings the tragic “My Man’s Gone Now,” a beautiful, operatic dirge. The transition from this into “Leaving for the Promised Land,” a gospel in which Catfish Row accepts Bess, goes from zero to 60 in tempo as the cast suddenly begin to dance around the corpse. Similarly, the transition between the climactic “Bess, You Is My Woman Now” and “Oh, I Can’t Sit Down” is rushed and seems to exist solely to finish the first act on a dancing number.

“The Gershwins’ Porgy and Bess” functions best as a showcase of Lewis and McDonald’s impressive performances. The technical aspects are top-notch, and the supporting cast shines; the updated language doesn’t seem out of place or distracting, and each musical number on its own is electric. However, the transitions between the numbers distracts from the overarching love story within, and some of the original’s coherence has been lost in the conversion.

—Staff writer Christine A. Hurd can be reached at churd@college.harvard.edu.