I love hi-tech, hi-def, hi-res, hi-powered, hi-quality, hi-everything and have to have it the day it comes out - but I can't tell a differerence. I stood in Best Buy watching the split screen (BR and non-BR) for several minutes and couldn't tell. And yes, I was standing far enough back not to need my reading glasses.
I'm sure glad some people can tell a difference. For me, it seems to be an attempt to count even more of the stubble on Indiana Jones' chin. I can do that with my $70 upconvert DVD already (if, of course, I was so inclined). There is only so much input one person can take.
The Blu-Ray of Cars is where I can see the most obvious difference. Did you know that Lightning McQueen's paint job sparkles? I don't mean his post-Ramone paint job...