The only reason I'd get it, is if the apps were less buggy. I doubt that will happen. Most are written by third-party brogrammers, and it shows.
Otherwise, there's not a thing that this offers, that's worth shelling out another 300 bucks.
I have the original 4K, and watch it all the time. I'm glad it has the double-tap Home button (swipe up to kill the app). I use that feature a lot.