I have that one, looks gorgeous at 92" and that's one of the lesser looking blu-ray releases. It only scores 3.2/5 for picture quality on blu-ray.com, only so much you can do with an old 35mm print. Compare with 2001 made from a 70mm print, could not believe how much better that looked than the dvd version. Most older movies are worth the upgrade. I recently imported princess mononoke on blu-ray. I have watched the dvd at least 15 times, and in the blu-ray version I immediately noticed the extra detail and the lack of compression artifacts. Plus the sound was a big improvement as well.
Most HD streaming doesn't get you much more than upscaled DVD quality. Sure it's nice when nothing is moving, when the action starts it becomes a blurry mess that doesn't look much better than dvd.
I still have over 400 dvds, still watch them too, but the quality difference is indeed huge. You can upscale 720x480 all you want, you're still stuck with a bit starved mpeg2 encode running 5mbps. The amount of compression edge noise is very distracting. Add in chroma subsampling that quarters the color resolution, which is ok for a 1080p stream, yet upscaling 360x240 color info is just plain ugly.
The switch to digital cinema hasn't done blu-ray any favors either. Early digital movies don't look all that great. Lotr's 2K master is very soft, definitely not reference material. Nowadays the quality has gone up leaps and bounds. Better encoders, 4K masters, new blu-ray releases generally look stunning.