Got a couple, upgraded from two Sony A9.
Better grip than the Sony A9, my Dad liked it too over his A73.
EVF is super, nice big clear.
One of the biggest things over the A9 for me, is lack of interface lag - worst for this is group photos, you take a photo realising you're shooting wide open - roll the wheel to stop down take another photo, the aperture never changed. I noticed just today at how you can change the aperture immediately after taking a photo - it's so welcome when you work at a thousand miles an hour
I found out the A9II has antiflicker, but the A9 didn't and the A1 does - so I'm looking forward to shooting theatre with this.
Lightroom Adobe Color presents the A1 files nicer than the A9, colour is better - no more magenta cast.
Easy to burn through memory cards with 50MP @ 20 fps, I'm not sure I'll ever bother to use 30 fps - particularly since you have to use lossy compress raw, instead of lossless.
What else is there to say? the AF is obviously super, but I didn't expect anything less.