Watched episode 3 last night and I thought that one at least looked really good. Of the 3 episodes I've watched to this point, I was only really distracted by inconsistent grain in The Child.
"Elementary, Dear Data" has held up as a pretty good episode, mostly due to the enjoyable performances and strong dialogue. The period costumes are a lot of fun as well.
This episode is known for having a few flubs and I noticed a couple of more on this watch: in the first holodeck scene, Geordi professes his unfamiliarity with the material, but then a beat later he's writing in his journal in the Watsonian style. Also, when he's writing, if you look at his hand movements it's clear that he's not actually writing and is just scribbling in the journal.
I'm not sure if blu-ray was necessary to catch that one but I thought it was kind of funny.
Then there's the scene where Geordi is holding the drawing of the Enterprise, upside-down, before he flips it, right side up, to the camera. This is widely known, but on the blu-ray you can actually see the upside-down enterprise through the partially transparent paper before he flips it to the camera.
I'm nitpicking the episode but I do like it, it's my favorite of the first 3 episodes for sure.