Played about 3 hours now, still very early. Initial impressions are good, it's hard, like it's supposed to be. There was one area where I crashed two times to desktop upon loading, but otherwise there aren't any major, obvious issues that I've come across yet (still early, though, as mentioned). There are smaller issues, such as your flashlight being turned off every time you load your game, or the actual loading times of the game itself (I don't think those with slower SSDs than mine will have a good time with that).
The atmosphere is amazing, and I like the gunplay, even this early on. Combat lacks a little weight, but is satisfying. Fighting humans is much more fun, but there have been minor issues with the AI (stuck in a "loop" of path when looking for/taking cover, for instance).
I don't regret buying it day one, I was prepared for some jank in the beginning. As I've said; this has the making of a future hit once things get ironed out. It's refreshing with a shooter that isn't afraid to kill you time and time again already at the start of the game. I have to go to bed now, and I have work tomorrow, but I'll be putting in many hours this weekend for sure!