These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Padding: It's been suspected that the paint/thinner mechanics add to this, as the gameplay has to pause constantly while Mickey's animation for painting and thinning is being done.
Sequelitis: Averted; this game has been better-received than its companion game, Epic Mickey 2: The Power of Two, which it also surprisingly outsold, and is on par with the first game in terms of reception. That said, there's still a lot of room for improvement.
Though these wouldn't be so bad if the game either saved after a rescuing a character and collecting quest items that appear in the levels or at least had a midway point marker that saved your progress at least, rather than only saving after clearing long screens, it's really bad for those who want to hundred percent the game, because should you die after collecting a quest item or saving a character but have yet to get to the next screen you'll have to go back to where you found them and collect/save them again, and as stated above this especially bad during the Under the Sea part of the game.
They Wasted a Perfectly Good Character: Mizrabel turns into Gaston briefly during her first appearance. She never takes that form during any of her boss fights. Particularly notable in that Gaston has rarely ever appeared as a boss in a Disney adaptation game, despite many fans wanting to see him as one.
She even took on the form of many other villains like Scar and Hades. Neither were battled nor found.