My copy arrived yesterday and I've listened to the mixes several times. The good news is that the Atmos mix played on the blu-ray sounds noticeably better on my system than the Apple Music stream. It has more detail, separation and punch - undoubtedly due to compression and processing issues with AppleTV. Generally I'm very happy with AppleTV/Apple Music streaming for the price but it won't replace physical media in quality.
I compared the 5.1 mix (which I had not heard before) to the Atmos mix, and frankly IMHO Atmos just blows it away. The addition of the height channels plus the separate side and rear channels, which Steven Wilson aggressively uses, results in an often stunning, immersive listen. It's by far the best way to experience this release.
Musically, while I like this album, I don't think it's better than prior releases. PT has a very strong discography, especially the final string of albums before the hiatus: In Absentia, Deadwing, Fear Of A Blank Planet, and The Incident, all of which brought them global fame. While I think In Absentia and FOAB represent the pinnacle of their output, each of those four albums contain several outstanding tracks that are defining for the band. This new one may grow on me, but so far, fewer tracks are hitting me the same way.
Finally, I have to say the "deluxe" package is... underwhelming. Thin, oversize cardboard with slots to hold the discs (one of which was loose when I opened it), a softbound book with obscured photos and little info, and a nearly empty blu-ray is not impressive. I own all the deluxe surround editions (on dvd-audio) of the prior PT catalogue and in addition to 5.1 mixes, they contain a wealth of additional A/V material including bonus tracks in surround, videos, photo galleries and lyrics. To not include the 3 excellent bonus tracks, or instrumentals, or any video material on the blu-ray is mystifying, especially at the price.