The actors in Arizona Repertory Theatre’s production of “”Into the Woods”” all deserve medals just for getting through this marathon of a musical.

That’s not to say the production isn’t enjoyable; parts are positively electric. But at a little more than three hours, including intermission, audience members should be prepared for a whole lot of lyricist Stephen Sondheim’s musical moralizing.

Sondheim’s fractured fairytale on steroids sets characters from a variety of familiar stories — from Little Red Riding Hood to Cinderella to Jack, of beanstalk fame — on a collision course with one another. As their paths cross and their motives become increasingly convoluted, the characters sing and skip their way through the woods (a blunt metaphor for moral ambiguity), moving toward a cheery resolution. At the end of act one, all the characters have exactly what they want.

Of course, in act two, it all goes to hell.

The acts have such vastly different tones that it was almost as if each actor had to play two completely different characters. Max Nussbaum and Caitlin Kiley, as the Baker and Baker’s Wife, proved particularly adept at this task. They transformed their bickering couple on a quest into a flawed but surprisingly redemptive story of transgression, loss and the ability to carry on. Both transcended their fairy tale archetypes and injected their second act performances with emotional honesty.

The actors in ART’s production performed the show’s almost impossible musical numbers admirably. The second act in particular featured a handful of stunning vocal moments, especially the melancholy “”No One is Alone”” and the magnificent finale “”Children Will Listen.””

Some actors occasionally veered off key, especially in the more talky numbers. There is, in fact, very little actual talking in “”Into the Woods,”” making the actors’ ability to carry the musical vocally all the more impressive. A few showed the strain, their voices less certain as the evening progressed. This was distracting mostly because one longed to run onstage and offer a few of them a throat lozenge.

The production values in this staging of “”Into the Woods”” were staggering. It’s a play that demands a convincing set to avoid being completely hokey, and the dark, atmospheric forest created by scenic designer Clare P. Rowe exceeded expectations. The lighting, designed by Zachary Ciaburri, was similarly stunning. From lifelike sunsets to the eerie, green light filtering down to the forest floor, the lighting design brought the stage to life in a way technical elements rarely do.

The costumes were also extremely high-quality, but sometimes seemed better-suited for a Halloween party than the staging of a musical. Brian Johnson’s Wolf had one of the show’s most fun numbers, “”Hello, Little Girl,”” but was held back by his beautiful but bulky costume. He was saddled with a full wolf head, from which his singing emerged warped and muffled.

The costuming problem was more evident with the show’s indisputable star: Sarah Baron as the Witch. Throughout the first act, the witch is, well, witchy. Only in the act’s final moments is she transformed back into her true, beautiful self. And while Baron’s witch costume was visually interesting, it was so heavy and overdone that it hampered her bewitching signing and acting.

Despite this costuming drawback, the production positively belonged to Baron. She seemed to shoot bolts of energy into her fellow performers every time she strutted imperiously into a scene, and her singing voice was the most exciting, textured and varied by far. She didn’t steal the show, for such a verb implies sneakiness and malice. She simply owned it.

Though long, Arizona Repertory Theatre’s “”Into the Woods”” proved well worth the journey. Its actors and technicians seem to have worked equally hard to bring this tricky musical to life.