I started to play A21 this week (taking a break from Diablo 4 and the atrocious patch 1.1) and by arrogance as a veteran player (over 3k hours) my chosen map was 66% wasteland, 17% snow and 17% desert. I said to myself "this new system can't be too punitive". I have learned the hard way it can and will. My original spawn was snow and I died on the very first day, got ferals, cops and radiated zombies on tier 2 quests day 3 (died twice due lack of gear), day 7 horde (gamestage 85) couldn't finished it with 160 pipe bombs and 350 9mm (there was a lot of zombies and already killed over 300. I was baffed. I played full wasteland map on A20 and only saw over 300 zombies on horde night by day 35 at the bare mininum, never this early as of today. It's true I play 64 zombies and warrior settings, but A21 is definitely harder in general, specially starting outside forest.
I always critized the new magazine system because I'm a solo builder, but it seems block damage is higher so you spend less time and it's a good trade off. The new water system is amazing as I expected: you definitely have to face hard choices sometimes.
I'll start a new map tomorrow, no forest again, but with a larger desert area which could be a bit more friendly than snow (thinking 56% wasteland, 17% snow and 27% desert).