Now having watched the entire film (JVC DLA-HD350 projector, filling a 120" 4x3 screen), I first want to say that I'm in full agreement with Robert Harris's assessment of the quality of the Blu-Ray image, so my comments are about the the way in which that quality affected my reaction to the cinematic experience of the film. I've seen it countless times over the past 50 years, both theatrically and in just about every video incarnation. Despite my familiarity with the film itself and, particularly on video, an awareness of the technical aspects of its presentation, it's never failed to involve me in the story, its characters and its narrative flow. The Blu-Ray, though, brought something new to my experience, something I wasn't quite prepared for. I won't go so far as to say it was disturbing, but I did find that it had a tendency to take me out of the film in a way that nothing had before.
The best way I can describe it is that the very clarity with which the transfer rendered the cels often made me feel like I was perusing a gallery of animation art rather than watching living, moving images - I didn't get this feeling from the backgrounds or the various multiplane paintings, just the cels, and those primarily in more static or slowly-moving actions. Their very crispness heightened the awareness that the cels were indeed discrete shapes inhabiting their own dimension, rather than being objects moving about in the overall space of the scene. Undoubtedly, this spatial disconnect is something that the softness of the original Technicolor prints (and for that matter, standard-definition video) would have helped mask.
So on the one hand we have a wonderful presentation of artistry and technique of the Disney studio in the late 1930s, one which I'm thrilled to have on those terms, make no doubt about that, but on the other, one which introduces a new element that, at least for me in this initial viewing, tended to distract me from the full involvement in the film itself. Maybe that will change over subsequent viewings - or maybe I'll try de-focusing the projector lens! Anyway, it's an interesting new wrinkle in how we're able to perceive older films with new technology.
On a separate note, I continue to be annoyed by Blu-Ray programming gee-gaws; for example, the navigation graphic that lingers over the bottom of the image for several seconds after releasing from pause. What purpose that serves, I don't know.