"I am Oz the Great and Terrible". That's what the wizard says in the 1939 classic (and the book before it) when Dorothy & gang come before his throne.
This movie just has a terrible script. Terrible lead actor (Oh if only Johnny Depp or Robert Downey Jr had said Yes!). Mediocre acting from others -- except Rachael Weisz - more Brits please! and fewer American TV ensemble actors from shows about troubled teens.
The CGI/special effects are wonderful. I nearly plugged in my earbuds and put a white noise track on my MP3 player. So I wouldn't have to listen to the terrible script/acting and could just concentrate on the pretty pictures.
Every joke went over like a lead balloon -- not a lovely hot air balloon. No one in my theater laughed at one of them. Even the cute animal sidekick (here voiced by a white actor, in a surprising turn) just fails to be cute or funny enough. (And I liked Zach Braff in Scrubs).