I've reviewed the set too and my reaction is much like many others here.
I didn't look at SOUTH PACIFIC or THE SOUND OF MUSIC since they're the same as earlier releases.
STATE FAIR -- given the state of the elements of Fox's older films, I think it looked pretty good, a little on the ruddy/brownish side and maybe a little dark but not disturbingly so.
OKLAHOMA! -- Cinemascope. Fine with me, looks like the DVD but in Blu-ray. Todd-AO. Todd-OK!!!! Spendiferous. Just like I remember from the TCM festival although now (sadly) on my small (compared to the TCL Chinese screen) TV. I really think 20th Century-Fox should release this in theaters for a few days, like a long weekend. I think it would be a bit hit.
CAROUSEL -- way too dark. Objects in shadow turn into formless blobs. Also, coloring too blue and gold, like THE KING AND I.
THE KING AND I -- I didn't watch all the way through, I mostly concentrated on the opening scene and the coloring of Deborah Kerr's dress. Or thought that would obsess me, but along with the dress and its randomly transforming hues, I was also highly annoyed by the weird gold push given to skin tones and the woven baskets on board the ship. Rex Thompson's shiny hair has the same ugly gold highlights. On the DVD, everyone's skin looks normal and the baskets are realistic beige-light brown colors but all that is gold on the Blu-ray. What's not gold is blue or blue-ish. On the DVD, Kerr's dress is blue-gray and stays that way throughout the entire opening sequence from the ship to the palace, except during the longshot walk to the palace, where even on the DVD it looks blue. But it's back to its normal blue-gray once inside the palace. On the Blu-ray, the dress is various hues of blue-gray while on the boat, then blue during the walk, then very gray when they arrive at the palace, and once Anna meets the king, the dress becomes progressively bluer! It's the darndest thing. The only other scene I watched after that was the banquet/"House of Little Thomas"/"Shall We Dance"/capture of Tuptim sequence where I was relieved to see that Kerr's famous champagne ball dress stayed the same color throughout, though there were shots especially towards the end of that sequence that looked sourced from a different element with noticeably poorer detail.
So what's going on with 20th Century Fox and The King and I???? (And Carousel too.)