Anyone who is using a lot of iMovie and or heavy gaming isn't going to use an iPad but a Mac of some kind
Depends on how you use it. If you want to run demanding games on the go or places where you wouldn't take Macbook then the iPad is a great fit. Same goes for iMovie, if you had your iPad on holiday and wanted to render simple but lengthy movies then again the increased horsepower in the 4 is a good fit.