well, from videophile point of view, it appears to have less details than 1080 BD but then again you gained HDR and WCG from 4K UHD and i think this is really subjective so you might need to judge this yourself...
anyway i attached here,
Oblivion 1080 BD / 4K UHD comparison PQ so you can give it some thoughts, please be noted that they can't capture HDR to show on normal screen so the 4K images here and on your screen TV would look different but you get the idea, overall you'd see that 4K PQs appear to look good through out but check these:
(1080BD / 4K UHD)
if you look at one image of Tom's mustache close up you'd see that on 4K the details are lesser and becomes blurry on 4K
next capture close up on his would face, on 4K it appears to be blurry...
next capture from spaceship, on 1080 BD you can still guess the word ODYSSEY? but on 4K you can barely read it...
so there you have it, hope this helps...
*source HD-Numérique, la référence 4K Ultra HD Blu-ray, Blu-ray et Home-Cinéma pour les passionnés