Never combine, drag files onto taskbar items to open window, clocks on secondary monitors, taskbar in positions other than the bottom, small taskbar, option to always show all tray icons instead of having to set it per app, right click not having most of the options unless you right click the start button. A lot of the functionally focused options are gone.
Not that it's 100% bad. Ability to fully disable the show desktop region at the end of the taskbar, the combined volume/network/quick settings icon region, the general redo of the popout for quick settings, the search not being larger than everything else in the taskbar by default, the notification region merging with the clock region, and the general styling update are good. It's just heavily outweighed by the bad... and the broken.
The still broken even though they rewrote the whole thing including things like the new menus often getting stuck open even when you click away from them, auto-hide taskbar on secondary monitors still having issues popping up, the start menu always opening on the primary monitor when you press the win key even when you're active in another monitor, the new "Chat" Teams client that integrates with the taskbar still not supporting corporate accounts, sudden rapid fire 1 by 1 bursts of notifications about the emails I've gotten and already responded to in the last hour despite focus assist being disabled, and I'm sure more I can't think at the moment.
Also the dislikable additions which are of course preference based but I think most people will find things that received a lot of effort like widgets and chat useless.
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All that being said it's still livable for me but it is a definite downgrade and a bit disappointing.