Sound - It's quiet.
Similar in volume to the laptop rubber dome keyboards I have (which themselves are quiet for their type) but with a crisper, less mushy sound. Sound varies quite a lot with the surface it is on. On a solid desk it's near silent if you type softly. At the other end of the spectrum using the box as a base is as loud as a mechanical keyboard but more 'clack' than 'click'.
Home Row Edit & Cursor - Is awesome.
You don't need a Textblade for this, I was already using something similar via Autohotkey PKL but I can't believe this hasn't become mainstream long ago. TB is going to force you to learn some of these tricks and you'll love it once you do.
Speed - A few days in I have most of my normal speed and it feels like it should be no problem to get all of it. Previously I was about 70wpm measured here;
Currently about 50wpm with TB if I don't make to big a mess but sometimes I have a clumsy run and might be as low as 40.
I'm very encouraged by the sense that normal speed seems pretty easily achieved. We've seen fast typing in WT vids but you never know if that is only achievable by a WT staff ninja with 3 years practice, 10 espressos, & a tote of amphetamines.
Robustness & Durability - When stowed correctly it seems like it could take a fair beating, I think you could drop it a lot and not have a problem other than cosmetic.
Since there is no complete outer case I do wonder about ingress of lint etc from pockets, but when stowed the keys collapse so kinda seal the underspace. They are also face to face in the center of the stack so not exposed drops & knocks.
When separate the keyblades flex very easily, they seem a bit flimsy and I was worried they are fragile so initially I was handling as if delicate.
This seemed at odds with the every day pocket portable concept so I asked about it during the call. Turns out it's deliberate. It helps grip the surface & make it stable, avoid rocking etc even if on slightly uneven surface. It's also perfectly ok for them to flex quite a way so basically don't worry about it in normal handling.
You won't want (or need) to put them in a pocket without the protection of the stack. When separating blades or pulling off a metal surface its better to prise at the wedge end as that is where the strong attachment is.
Best to add the Spaceblade to the stack with shiny base facing out as the magnetic binding is much less strong so easier when comes time to separate.
I might be guilty of experimenting with ways to separate & deploy with maximum flourish & flair.