I have waited for years for a Broadway revival of the 1978 musical "On the Twentieth Century," a screwball comedy about a down-on-his-luck Broadway producer and the Hollywood actress he needs to star in his next project. Otherwise, his career is finished.

It has a rich and melodic score that brings operatic heights to its characters' over-the-top narcissism.

Although I am too young to have caught Hal Prince's original production with Madeline Kahn, John Cullum and Kevin Kline, I have listened to the cast album repeatedly for years.

The Roundabout Theatre Company's new production with Kristin Chenoweth and Peter Gallagher doesn't live up to all that the musical could be theatrically, musically and comically.

That being said, the production is still pretty damn enjoyable. To speak metaphorically, the glass may not be full, but it's certainly more than half full.

It features a glimmering deco design that depicts the train exterior and interior, though the size of the cast and orchestra really ought to be beefed up.

Chenoweth, with her rich singing voice and knack for comedy, was born to play diva Lily Garland. She has the audience in the palm of her hand, but her performance reflects the same larger-than-life persona she's become identified with.

Gallagher, who missed numerous preview performances due to illness, lacks the robust voice that Cullum brought to the role, but captures Oscar Jaffe's maniacal egotism and dashing spirit.

If the production extends its run, maybe a stronger singer like Brian Stokes Mitchell or Douglas Sills can take over the part.

The supporting cast is thoroughly terrific, including Andy Karl ("Rocky") as Lily's brainless beau, Michael McGrath and Mark Linn-Baker as Oscar's harried staffers, Mary Louise Wilson as a religious nut and a quartet of sunny, tap-dancing train porters.

If you go: “On the Twentieth Century” plays through July 5 at the American Airlines Theatre. 227 W. 42nd St., 212-719-1300, roundabouttheatre.org.