I'm just looking through the release notes right now, and I'm really pleased to see all the places this release is cutting down on superfluous options and confusing syntax!
Being able to go back and update locked in content to keep well ranking posts relevant is a pretty wide-ranging addition to a release that already has a lot of great implications for performance and stability. I think this will definitely change the way I think about writing my content, as I've shied away from certain links or styles, knowing that it's always only been unidirectional up to this point.
Otherwise... I'm looking forward to playing with all the new toys! Thanks for this solid continuous push towards improvement; it's exciting to be a part of it all.