There's the new poop emoji!! (unicode 10 emojis via 10.13.1 update)
Real answer, APFS (which changes the Filevault encryption model to no longer be full-disk-encryption...) and Metal2 graphics (which has brought a variety of new gfx bugs into play, even for 1st party applications) are the big technical draws
For a full list of changes, review the marketing page or the developer release docs
- https://www.apple.com/macos/high-sierra/
- https://developer.apple.com/library/content/releasenotes/Mac...
(yes Apple can't be bothered to update their dev docs with the point releases. Documentation quality has fallen off dramatically since the 10.6 days)
Given the stream of bug reports on various apple sites, I have not upgraded any of my personal machines, and my employer has stated they will not be upgrading our machines in the near term.