I played through the starting phase a bunch of times but had self-imposed myself a permadeath rule (since I thought I would have to restart a world anyway once the update drops)
I'd say I'm pretty comfortable up to the start of the copper age, but I do understand that it's basically the start of the game still lol
Having said that, I'm going to hop on the 1.22 rc10 client and just start playing! By the time I get to any of the new features, the last few polish fixes will probably have come out already! Fingers crossed it all goes fine and I don't have to restart any time soon!