Very sexy technology, I'm sure one day it will become the norm. I didn't see the power consumption mentioned, I would hope that it's more efficient than the current LED back light technology but right now we can only guess.

Of course this will add a huge chunk of cash needed for a PC build with a nice graphics card that can handle 4k at a sensible FPS. That's progress for you, it cost a lot.

Having an OLED screen on my Galaxy S5, I have first hand issues with burn it. It is mild and only noticeable on a totally white (or bright) screen.
I have no such issues on my old HTC One M7 which had an LCD 4 screen.

The main difference is contrast ratios and blacks. Unless you have them side by side, they're both very good and you'd never notice.