4K TV owner reporting in. Barely any, and by this I mean,
BARELY ANY blu-ray media exists that displays in 4K or even 1440p resolution. If you run 1440p or 4K, then it's for the intent of gaming on a PC. Otherwise you're best off with a 1080p 30hz TV. (Seeing as The Hobbit is the only mainstream release I can think of that is filmed at 48FPS and thus can take advantage of 60Hz).
That said, thanks to pixel density, even upscaled 1080p media looks good on 4K displays, but there's still visible pixellation.
Was the refresh-rate around 120Hz? My LG HDTV is LED and is 60Hz but I have no idea what the refresh-rate is on my brother's HDTV. His does have MotionFlow, which takes the "filmic" 24 FPS and turn it into something much smoother. I was watching Kingsman: The Secret Service on Blu-ray that he ordered a few weeks back and it looked very damn nice.
Yeah, misconception. 120Hz does nothing for 24Hz media. (Except possibly giving motion sickness.) When my TV runs in 1080p mode it switches to 120Hz and there's no visible difference. Again, games running in 120FPS on the other hand... That's noticeable.
Whatever that MotionFlow thing is, well, I don't know, but unless it functions on a software level like SVP, it's probably just placebo.
Like I said, if you're only watching movies/TV on it, you're best off with 1080p 30Hz.
Clef is right though. Any Blu-Ray before HD became mainstream is probably just upscaled and won't look better than a DVD, typically.