just dual booted PB1 on my 2020 Air and some basic observations:
I don't mind the new transparency UI and more 'congealed' window appearance. Heck, don't even mind new icons on the dock, new CC, or the iOS 14 like widgets instead of NC. The rounded corners I almost don't notice, unlike on X iPhones where I always find it a bit too intense (but nothing can be done about that)
I think there's too much forehead and deadspace on Safari window header, but hopefully that gets fixed.
Didn't like the spacing on iStat by default even though its 3rd party, but was fixed toggling Combined option to enabled
Overall: not bad
Also, at the same time not seeing a huge feature set difference from Catalina for the couple hours I've been tinkering (though Safari 14.0 having tracker detection built in is pretty nifty) and haven't given messages a thorough rundown, to warrant the 11.0 name but but yeah. I guess Apple silicone supported OS is what will 'pave the way' for the 'future of Mac' (ok where's my paycheck now, Craig and Tim?)
Its a little thing but I like the keyboard brightness slider in CC
Gives us non-touchbar users a little slide action
The graphics driver at least in relation to my model Mac seems a bit regressive from Catalina, the minimize window animation at time lags, but I've experienced this before with beta OS'es. Just hope it gets ironed out by public release. But it's also not terrible, I've experienced worse regressive graphics drivers in years past.