The DVD's PQ was, in a word: awful. No clean up of scratches, picture soft. No subtitles or captions, either.
So I hope they do the Blu-Ray right.
Also, the DVD was in 1.33:1 as it was a TV production. Lonesome Dove came out all right as a widescreen Blu-Ray, even though it resulted in cutting out the top and bottom of the original 4:3 picture. I don't think Jesus of Nazareth would fare as well. The German Blu-Ray you link to shows 1.33:1 fullscreen. I hope the U.S. edition is also 1.33:1.
But they really need to restore and clean up the image - without much DNR, hopefully!
Concur, the leap in detail is very nice but something about the colors looks off in those shots.
Yes, it looks like in the Blu-Ray we're getting the detail of a high-quality DVD and the grain appearance of a Blu-Ray. Maybe the apparent softness of the picture (compared to other Blu-Rays) is due to the way it was originally shot.