The initial thread question seems like a trick question to me. Having watched the TOS Blu-rays I'd say that about 75-80% is TNG-R quality while you have about 25-20% live action footage one would have expected to have more resolution and detail from the original negatives (such footage is rather movie BR quality). But I don't use a flat screen but a front projector, thus those quality differences are easier to notice on a big screen.
The gain in resolution and picture detail is impressive, but I really don't like the encoding of some of the Blu-rays. When I select the original effects in the menu prior to starting the episode I expect to have the original effects from the start on and not with a few seconds delay. "The Ultimate Computer" begins with the new effects and then switches to the original ones, in "Wink of an Eye" I had the whole opening scene with the new effects before it switched to the original ones.