I skipped around a bit...Tin Man...looks...absolutely...amazing. It's hard to believe they use the same FX elements. Booby Trap left my jaw on the floor. Im also noticing fewer grain isues in season 3 which makes me love the set even more.
As I've gone through the set, some episodes look amazing, whilst others such as "A Matter of Perspective" look a tad murky. Although I'm sure it has more to do with how the episode was shot rather than the remastering process.
Grain however is far more balanced than what we had to deal with in season 2.
You're both right, the grain is finer and more balanced this season due to an upgrade in film stock. I posted this over at Blu-ray.com, but I'll go ahead and repost it here in case anyone's interested:
It's not really anything CBS is doing differently, it goes back to the film stock that was used during production. Season 1 was filmed primarily with Kodak's EASTMAN Color High Speed 5294 400T Negative film which has a rather coarse grain structure overall. I believe Season 2 used 5295 (400T) which was optimized for bluescreen work.
Then in 1989, Kodak introduced their EXR line of stocks to celebrate the 100th Anniversary of Motion Pictures. These stocks had a much finer grain structure compared to what came before (so called T-Grain stocks). Tabular grain stocks were developed by Kodak to standardize the size of the silver halide light sensitive crystals so they all have roughly the same surface to volume ratio. They generally look like flat triangles or hexagons in electron microscope images
Season 3, in addition to having a new director of photography, Marvin Rush, uses EASTMAN EXR 5296 500T Color Negative film for set interiors. This stock has tabular-shaped crystals in all but the fast yellow layer (a blue sensitive layer). This is why you may see heavier grain in bright blue colors while everything else looks pleasingly fine grained. You can notice this a little in the episode "Yesterday's Enterprise." Marvin Rush put blue gel on the ceiling of the alternate 1701-D bridge. Notice the heavier grain in the blue channel, while the rest looks fine (click the image to enlarge):