This is very, very good news. Shiny and new is nice and all, but mostly I just want what's already there to work better. Windows has been aggressively not doing that for decades, and the Mac has been doing the exact opposite recently.
But honestly, speed is not a thing I've complained about for years. What I want is reliability. The coincidental AirDrop emphasis in that screenshot in particular: AirDrop is awesome. I love it. I want to use it all the time to get stuff between various devices in my home. But the reality of it is that it just does not work reliably, and there's never an explanation--devices just fail to appear, or files fail to send with no error message.
Going from my phone to Mac, in particular, I'm pretty sure I have to reboot one or the other device to get it working at least every other time I try. The feature is awesome when it works, but that when is so uncommonly "on the first try" that it feels less like magic and more like a lie.
It does seem to have gotten better very recently, so perhaps there's already some work happening under the hood, but basically I would be far happier to see improved reliability of existing features than any other thing Apple could offer.
And don't even get me started on the Mac-side UI backsliding recently. Take Maps as a simple option, latest version, 26.5.1:
Click a location. Click Directions. Click "My Location" to change it to some other starting point. When the panel switches to entering a new location, the "My Location" text in the entry field is selected and it has focus, so you can start typing and it will replace whatever is there, which is exactly what you expect and has been the case since the '80s. Except due to the last place you clicked, the mouse is now hovering over the top of the suggestions list, and if it moves even a single pixel before you get your hands to the keyboard, focus switches to the list and the text in the box gets de-selected.
So not only can you now not just start typing--you get a bunch of error pop sounds instead of text like you expect--but if you now click the text entry box again, nothing is selected, so you have to triple-click or click and command-A in order to select the text and delete it to get whatever you actually wanted.
But it gets worse! You see the item you want in the list below, so your instinct is to hit down-arrow to select it. Except down-arrow does nothing, you need to hit tab to switch focus to a list that has no indication it's a different region in the popover instead of an auto-suggest drop-down like it should be, and then you can arrow down. Or you can mouse over the list and have it instantly steal focus from the text entry again, at which point the arrow keys work, but typing the first letters in the list item to hop to it does not. But even that's a lie, because while you can use the arrow keys to move the highlight down the list, hitting return... does nothing. Doesn't populate the box above, doesn't confirm the selection and go back to the previous page, nothing. So the highlight controlled by the arrow keys is an utterly useless placebo, the only way to actually do anything with the selected item is to go back to the mouse and click on it.
All of those UI things were solved decades ago, and have worked well for my entire professional life using a Mac. Yet here's a first-party major app from Apple that can't even get text-box entry correct.
Fix the broken windows and leaking pipes before you start remodeling the Kitchen or adding a whole new wing to the house.