What player are you using?I finally watched the first film last night in 4k. While I can see the changes in color, I have to say this presentation was excellent. I've been watching this movie for more than 35 years and it never looked as clear or crisp to me. The scene outside the hospital - long one that suffered from being too dark, with many images lost to the inky black - was easily discernible. The Christmas lights were like beacons. I felt like I could finally see that scene. (As opposed to, say, the end of The Deer Hunter, which I watched recently in 4k, when much of the return to Vietnam was lost to the disc being way too dark.)
I did have a problem - which was likely my player - at 2:01:00 in the movie, when it skipped the very end of Vito's conversation with Tom and went right into the undertaker scene. Less than a minute was skipped. I tried going back a few times but it didn't work. (I had updated the player's firmware just prior to playing the disc. Indeed, the disc would not play until I did.)
I'm still glad to have the blu-ray of these films ("The Coppola Restoration") and I will keep both side-by-side. I kind of think of it like the remastered episodes of Star Trek: The Original Series with the new special effects. The original versions of the episodes are there too, also in HD, but the new ones are also there for me to choose when I want them.