Like most special editions, it sounds like the additional content is probably worth an extra $10, rather than $20. Epic Mickey is still on my list, but I'll pass on the Collector's Edition if it makes it to Europe. In fact, the video developer diaries on the DVD would probably find their way onto the internet before too long.
EDIT: I looked closely at the box art just now and to me, it's an indicator that the marketing team has a good grasp of who the audience is for this game, which is certainly not the Disney Channel demographic. Although it is quite bare and simple, the art is suitable within the context of the game, and thankfully not the usual twee Mickey Mouse junk.