I just got my wife a Surface Pro 3 and now she doesn't use her iPad anymore. She rents movies, reads books, uses RSS via Flipboard, edits photos, installs apps and experiments with things. She also takes notes with the stylus, rips songs from YouTube and has Adblock installed in Chrome (edit: and after all that, she can throw it in the docking station connected to a 2nd large touch screen, keyboard and mouse) - things she could never do on an iPad.

So yeah, mobile is limiting but it doesn't have to be. Once you venture outside of Apple's cold embrace, many things are possible.