Just because some people like it, and even choose it, doesn't mean that it makes much sense. One minor issue is that if it were to fold in a way that felt physically realistic it would require going slightly above and below the screen, which it can't do (due to it being a screen), so there's something slightly unrealistic about watching it fold: some people don't notice, but some people will; the people who do notice may never be able to get past it.

However, we actually can ignore the whole problem of squishy design arguments: how do you deal with the PIN code lock? If you have a PIN set, the actual implementation of Unfold seriously unfolds the lock screen to show... another lock screen (?!)... that has the PIN keypad (ok, I guess)... and when you type in your PIN it disappears using the original animation. That's just... weird, and almost looks like a bug it is such a kludge when you see it.