SSS is in. A new top rank sits above SS, and every line under it moved down, so runs that used to flatten out at S finally show what they were worth. Nothing you already earned moves backwards: every saved result keeps its letter or gets a better one, and the same run scores more than it used to. Your old bests are sitting there, beatable. Go take them.
Songs start when you are ready. A level opens on a loading screen instead of a frozen first beat, and the count-in is five seconds instead of ten, so the wait is you getting into position rather than you watching nothing.
A gesture you half caught keeps your streak. A line of rings counts as one thing and a slide stops breaking in the middle, so the combo you feel is the combo you get.
Sound and tracking
Sound lines up. AUDIO OFFSET in settings dials out the delay your TV or speakers add, and "+" on TIMING OFFSET means later again, exactly the way it reads.
Tracking holds steadier. A phone lying on its side moves you as far as one standing up, a phone that reboots is found again without restarting the game, and ankles no longer flip around the shin.
New camera work. VIEW FOLLOW rides the body instead of watching from a fixed seat, marked PREVIEW while it settles.
Around the game
The menus got a proper pass. Settings are grouped into GAMEPLAY, BODY TRACKING, GRAPHICS, AUDIO, PLAYER 2 and SYSTEM, the results page and the leaderboards are redrawn, cards carry a rank badge and a difficulty chip, and text stays inside its frame.
Tutorial clips play on Steam Deck and on Linux. Where Proton could not decode the video they run as frames now, instead of a placeholder telling you it cannot play.