The improvements in the new macOS Sonoma consist of the improvements already shown in iOS and iPadOS. There are also new screen savers. This is mentioned first, so you can expect that there won’t be any real profound changes.
And so it goes: the widgets and their customization are put in the foreground. So if you use widgets extremely often on your Mac a fun evolution. If you only use the widgets for weather anyway, nothing really earth-shattering. At least you can now use the widgets on the Mac on the iPhone if it is nearby.
macOS gets a Game Mode, so gaming on the Mac should work better. Audio and controller latency should be kept at a minimum.
Very handy for video conferencing, though: Apple builds in a function that lets you fade in before the shared display content. That should be very convenient for many applications.