That's a phenomenal start for the game in North America. It hasn't been charting as well in the UK (which we get charts for, but not sale numbers) and Europe is more nebulous (very infrequent sales updates). The game has yet to be released in Japan.
Disney hasn't commented publicly on their expectations for the title, but I can't imagine anyone is disappointed. It has to already be one of the best selling Disney Interactive titles ever.
Hopefully if given the chance Junction Point can fix some of the game's problems in a sequel. And hopefully Disney will give them enough time to actually finish the game.
UPDATE: I have been told that Epic Mickey 2 has actually been in development now for "a while."
UPDATE 2: With the success of the game, I wonder if Disney will look to port it to the Playstation 3 (where it would work well with the Move controller) and the Xbox360 (which would have to use the standard controller, since I can't imagine it working well with Kinect)?
Warren Spector had mentioned before that it's something they would consider. May not be worth it though since the game is selling well enough on the Wii.