It does scale 1080p to 4K so if the scaled result looks better or not depends on the viewer
The so-called "SuperHD" on Netflix (less compressed 1080p) looks pretty good, too, and scales better.
The amount of 4K content available is poor as JEK said. A few Netflix series and you've seen them all. Sony has a 4K movie service with a media player but it works only with Sony TV's, Samsung sells a external 1 TB hard drive with five movies on it. Photos look great from an USB stick and the internet has some 4K clips, I've yet to try to install an Android app on the TV to stream photos to it.
We've had the curved 65" Samsung 4K for almost a month now and love it. It does look better in bigger size so I wouldn't go for anything smaller.
Just make sure you'll get HDMI 2.0 and HEVC support, there are models out there that won't support them.
I would like to get a 4K display in my home office and connect a Mac Mini or laptop to it. Unfortunately Apple's 4K support is pretty limited at the moment, one could get a 28" 4K monitor for $500 already so that's not an issue.