Apparently people are big fans of Snow White, as magic mirrors seem to be a hot new category of consumer electronics. Not that any of the devices calling themselves magic mirrors do the same thing; they apparently just like to pretend that their product is from a fairy tale and not some factory in Southeast Asia.
Anyhow, this iteration of the magic mirror is meant to be placed in dressing rooms. It allows you to "try on" clothes virtually, seeing what you'd look like with new threads without having to take your pants off. You can then send snaps of your new look to friends via text or email for herd approval, as you don't want to show up at the dinner dance wearing something your gal pals don't approve of.
Seems like you'd want to know how something, you know, fits, if you're in the fitting room, but what do I know?