The art style is a little too geometric on faces at times. But overall the visuals, background and animation smoothness are at the top end of anime I watch. I hope this is the basis for the season and not a one shot, because 00 is considered a movie/OVA.
For some reason, that intro to the universe was a lot easier to understand, with many subtle implications and all. But it might only be that I'm back to an universe I've been immersed in a lot of time.

It's been a long time since I played the VN, but that ep felt like an animated version of the beginning of that route, with no scene cut and no detail forgotten.

As for the Saber intro, it's a lot less powerful than Shiro's route. Just thinking about it wets my eyes a little.