Disney’s Oz the Great and Powerful is a fun movie, but only intermittently. The prequel of sorts to The Wizard of Oz (the film, not the book) has good performances, clever direction from Sam Raimi and mostly impressive visual effects, but its reliance on 3D takes away from its overall cohesion, and its sometimes-contrived scenes leave the movie riddled with plot holes.

Still, it is fun. Kids and parents will enjoy it, and those who like The Wizard of Oz will appreciate the many parallels between the 1939 classic and this one. But those looking for a deep and involved movie-going experience won't find it here. The rules of the witches' magic and the world of Oz are never clear, and if too many layers are peeled away, even the need for the Wizard in the first place isn't clear.

That said, there is a lot to love about Oz. The movie follows James Franco's character Oscar Diggs, a conman magician who works at a traveling circus, after he’s whisked away be a tornado to the magical land of Oz. There he meets the witch Theodora, played by Mila Kunis, who explains there's a prophecy made by the late king that a wizard named Oz will arrive and save them all.

To tell more would give away too much, but it’s safe to say the rest of the story involves a wicked witch or two, Glinda the Good, and even an array of Munchkins. All the leads of the movie shine -- Franco, Kunis, Rachel Weisz, Michelle Williams -- and the CGI characters played by Zach Braff and Joey King steal the show. Surprised? So was I, but despite early concerns it turns out Franco is the perfect man to play the Wizard of Oz. He’a conman and a liar, and no one plays smarmy quite like Franco, who makes Oscar Diggs both appealing and off-putting. It all works together, and Franco clearly doesn't mind playing up the story’s campy elements.

Taking turns as Franco's romantic leads, with Kunis plays the naïve Theodora and Williams portrays the good witch Glinda. Kunis is best before she gets covered in mediocre makeup and CG effects, but it's Williams who gives the better of the two performances. Weisz is Theodora's sister Evanora (her British accent is never explained), and seems to relish being the evil one for once.

The CG creations Braff and King play -- a flying monkey named Finley and a girl named of china named China Doll -- are the comic relief for much of the movie, and often draw the biggest laughs. As in The Wizard of Oz, Finley and China Doll (and Glinda, for that matter) parallel characters Oscar knew during his life in Kansas. But unlike Dorothy's departure in the original, Oscar's exit leaves the real-world versions of these characters better off. That's fine, because as anyone who's watched The Wizard of Oz knows, the Wizard won't return to Kansas at the end of Oz the Great and Powerful. His conflicts with those characters in the land of Oz mirror their Kansas counterparts, but unlike in the real world, Oscar can actually resolve them there. It's a nice tradeoff, and offers up a satisfactory conclusion.

The 3D was a major drawback at points for the story. I get it, 3D is here to stay, but if we're going to watch 3D movies, can studios at least ditch the corny stuff-flying-out-at-you-to-make-you-jump effects that were so popular early on in the craze? I actually enjoyed a lot of the 3D look for the vibrant world, but too often forced effects were an unnecessary diversion.

Take for instance the early portion of Oz, where the film is black and white and in a square aspect ratio, mirroring the 1939 original. Ignoring that it's ironic for a throwback to classic black-and-white films to be shot in 3D, there were frequent scenes when objects like fire would blow out the side of the visual constraint or directly at the audience and ruin the whole illusion. It was supposed to be "cool," but it's actually just silly. If 3D is supposed to be a more immersive experience, it's time for studios to really concentrate on making it so.

Oz works well as a prequel to The Wizard of Oz and (of course) there's still some room for an Oz the Great and Powerful 2. Although some parts of the movie seemed as if they were just setting up new rides in Disneyland -- large portions of the movie felt like a roller coaster, and not in a good way -- the film as a whole had a lot of heart and benefited from its actors' committed performances. Oz the Great and Powerful does what it's meant to do: remind us that the Wonderful Wizard of Oz might have been a little wonderful after all.

Oz the Great and Powerful opens today nationwide.