I used a VPN to unlock the game early, and I've been playing it for the past few hours. I'm glad to say that it's just as badass as I was expecting it to be (not that I was terribly worried; I gathered enough information from the previews and trailers to know that it was my kind of game).
One thing that surprises me is how much it accommodates stealth gameplay. There seem to be entire levels that you can sneak your way through. On the other hand, I guess all of the previous Wolfenstein games have had stealth to some extent or another. Personally I didn't buy the game to sneak around though. I bought it to blast nazis in the face and turn them into red mist with dual-wielding machine guns, and there is plenty of that here. I suppose it's nice to have the option. Sneaking can be a nice change of pace and the game gives you plenty of opportunities to go quiet.
Technically it's a very nice-looking game. Wolfenstein complements the idTech 5 engine much better than 2011's RAGE, IMO. Runs mostly at 60fps on the High preset at 1080p on my 7870, except for some larger outdoor areas where it drops down a bit. The texture pop-in bug from RAGE still exists a tiny bit (and it probably always will), but it's minor enough that you'll usually never notice, if it manifests itself at all.
Also, the soundtrack is legit. When I first booted up the game I spent a minute just sitting in the menu and banging my head to the music.
Don't forget the it also has a 7GB+ patch supposedly that needs to be DLed and applied after DLing the game itself. This thing is rumored to take up 50GB of space once its fully installed on your hdd.
The Day 0 patch is irrelevant to people acquiring the game digitally. It's already part of the Steam pre-load and you won't need to download anything extra.