Some first thoughts:
I'm eating my words about the dial. It is much better in person. Even with the sapphire, the "grey" effect seems to be crazily exaggerated in the photos. In all lightings I've seen the watch in so far, the dial is a consistent matte black. The concentric circles are clearly visible to the naked eye, and the step is also fairly sharp. Not at all the impression I got when looking at the leaked studio shots.
For everyone asking about how Omega managed to reduce the thickness, I'm pretty sure they removed the soft-iron cover, making the watch sit noticeably lower on the wrist. Now, the caseband/lugs sit flush with my wrist while the caseback disappears, whereas the previous generation casebacks would make their cases "float" a little above the wrist. Omega may have also resized the thickness of the caseband and crystal, but that may just be due to the improved proportions rather than an overall difference in thickness for those parts. The 105.012-style caseband is also extremely nice. There's something about it that makes the watch look both sporty and elegant, while the 1861's case profile always struck me as a little too thinned out at the periphery.
The bracelet is an absolute banger – I have so many things to say about it that I would probably have to start a new thread.
Will post a comparison with my 145.022-71 and Apollo-Soyuz Speedyorite once I have the time.
Oh, and the 3861 movement is beautiful.