What's DNR ?
Digital Noise Reduction.
Something they do to reduce grain and other "noise" in the picture, often taking away detail of the film if overdone (e.g. faces will look like wax). "Great" famous overdone examples are
Pan's Labyrinth (A) and to some extent
Gladiator.
Honestly, I was very very disappointed when I watched it. I know it was a bit naive of me but I simply assumed that a movie that is entirely based on visual effects would have been worked on to give us more on blu-ray than it did on DVD. My biggest disappointment wasn't about colors, it was about all grainy the picture was, looking at the pictures in Jon's link we can see that it's improved over DVD but that's not enough, no HD movie should be grainy like that, it goes again the very reason behind HD.
Grain is part of film. The higher the light sensitivity the more grain. Grain is what makes film film and removing it takes the movie it's life. Yes, too much grain looks ugly and I believe there is ways to reduce it a little bit without harming the integrity of the medium. HD by it's nature will show you the grain better, which was lost in the lower resolution of SD, but taking it out is wrong; you could just as well stick with SD.
Although, looking at a bad transfer often looks like a grainy film. So, we may be looking at the thin line here...
Bill Hunt at digitalbits once wrote a nice article about grain and DNR; very simple and easy to understand. If yu are interested I can try to find it again.
In Blu-ray reviews you will often find that the critics will mention DNR and usually not in a good way.
