Highlights include Sliding Sync (instant login/launch/sync), Native OIDC (industry-standard authentication), Native Group VoIP (end-to-end encrypted large-scale voice & video conferencing) and Faster Joins (lazy-loading room state when your server joins a room).
Did you find docs? I did a cursory glance around late last week and ended up just shrugging assuming that’s what I got for using Dendrite (positive)
Edit: Turns out, when running sliding-sync you really only need to patch the
.well-known/matrix/clientconfiguration