I'll restate what I said when we were talking about this in IRC. Take some of the original and unique characters from Alice in Wonderland, shove them into a generic hero's coming of age story, slather it in Tim Burton aesthetics, and you have this movie. I didn't dislike it as much as Sam did. Most of the characters were done very well, unfortunately the story wasn't. And yeah, Depp's Mad Hatter bounces back and forth from a lispy, frilly English accent to a caricature of a drunken Scottish rebel. I'm sure it was supposed to make the Mad Hatter seem even madder, but it was just jarring.
Oh, and one of the last scenes really bothered me. The movie had stuck well enough to the time period for the whole movie, then at the end the Mad Hatter does a dance to some really out of place hip hop music.