I have never seen The Wizard of Oz.
I saw Oz: The Great and Powerful last night and actually quite liked it. I knew nothing of the film and pretty much nothing of the 1930's original either so maybe because I had no expectations I enjoyed it more?
I do remember having a blonde moment at the end when I said "Oh, I thought they would have showed how Oz returned home at the end", to which I received a stare with raised eyebrow and a look of "Do you realise what you just said?!" Then I realised!
I liked all the cast, didn't think there was a weak one personally and the story had my attention throughout, I wasn't bored or looking at my watch. I even laughed out loud at a few things (a road sign for Oz's Chinatown district, really?!)
I'd give it an 8/10. (I really must watch the original though!)