It's interesting how sometimes HDR compliments old CG (the effects in The Matrix look great!), while other times helps show its age. In Jurassic Park's case I think that if Universal had not dialed back the grain as much as they did then it would hold up a little bit better. Things fare better in Lost World, partly because the movie came four years later which at that point was practically a lifetime in cg development, but also because there is a much steadier level of grain throughout as well, even though they dialed it back there too.
It seemed to me like Universal had a "set it and leave it" approach to grain management on these discs, rather than making adjustments on a scene by scene basis. So with JP, again never a grainy film to begin with, you still get some degree of grain in interior and night exterior scenes, but bright daytime exteriors, where film will naturally be its least grainy, suddenly look the most abnormally clean. I'm just thankful nothing looks waxed out as a consequence, but still scenes like the meeting outside the raptor pen at feeding time made my face scrunch up a little. Lost World, being intentionally a more grainy film throughout, meant there was enough left in daytime exteriors to still be visible on the disc, despite being toned down a few notches.
Only shot of one of the more questionable daytime exteriors extracted directly from the UHD that I could find:
The Brachiosaur scene is probably the is probably the best looking daytime exterior scene for its natural look, even though the grain has still been dialed back:
In fact the daytime scenes up to and including that scene in the movie all hold up well (so the dig site scene looks decent for example, though Dodgson and Nedry's scene at the cafe gets very soft and stands out probably the most of any scene in the movie on the UHD).
By comparison, things look nice enough in these kind of scenes throughout much of the film:
All credit for Pyoko at blu-ray.com for all the above. More screenshots (put alongside the same from the Blu): http://forum.blu-ray.com/showpost.php?p=15089907&postcount=773
So JP remains a pleasing disc that could have been a lot worse. Not as good as it should be, but this is pretty much true of any Universal release shot on film that pre-dates digital scanning/digital intermediates unfortunately (the 1999 Mummy being one of the few exceptions, and I was happy with E.T as well though there's debate about crushed blacks on that one). They cannot leave stuff alone, and not all their discs of movies shot on film that had a DI turn out great either! I didn't buy the UHD releases of Jurassic Park 3 or Jurassic World, but Jurassic World by contrast (shot on film, but had a digital intermediate scan) apparently looks spectacular with wonderful grain retention. It's weird how inconsistent Universal are.
Just spun Jurassic Park tonight. The color on the 4K disc is wonderful and really a noticeable upgrade from previous releases. As Daniel mentioned there is some DNR applied but nothing too egregious or distracting. Very pleased with it even though the CG effects work is truly starting to show its age in some shots. The animatronics still look amazing though and hold up beautifully.