I'm so happy that the cassettes will fit the 'old' Shimano freehubs. The move to SRAM 12 speed is going to be less painful when I can grab a few of the Shimano cassettes for my trainer and CX wheels. $112 USD instead of a new freehub and AXS cassette will save a ton of money.

I think a lot of people are going to be happy with the brake updates as well. There really wasn't much clearance in those calipers and I personally thought the previous caliper bleed 'solution' was a pain.