Probably too soon to ask, but have you noticed any differences (positive) between the XBox One X and the previous iteration?
I spent the whole day trying to configure the NAT settings and even though I can download updates and browse the store, I still can't make a new user account. It's a whole lot easier to setup the PS4. I have encountered this problem once before and it can indeed drive you nuts. Still trying to log in and create a user but I might have to check some stuff with my ISP and see if I can change my modem and get this thing running.
Check out your router before buying an Xbox, if it's old then it will likely give you weird errors while trying to sign-in or create an account.
As for console and the performance: It does give you some anisotropic filtering out of the box but the resolution depends on the game itself. If the resolution is locked at 900p on the Xbox One S then it will remain so on the one x. If the game happens to have a dynamic resolution then it will try to hit the max resolution possible. Some places you see less of a performance, most notably at places where the CPU is at work. Hitman for instance can't hit a full 60 fps when you are walking within a crowd of people. The CPU is rather a small upgrade(2.3 Ghz instead of 1.75 Ghz).
Then there are games that get updates and those updates usually range from somewhere between 50 GB to a 100 GB. Guess those must be the extra textures that are needed for a native 4K representation of certain games. 3 Xbox 360 games have received 1X upgrade as well and it is indeed magnificent. I recommend checking out this and this.
I'd say it's a very small, quiet and smooth console, especially if you don't have a 4K TV. I for one am not planning on getting a 4K TV soon and have connected my 1X to my 1080p LG LED tv. No noise or heat, huge upgrade from my OG PS4 which used to sound like a jet engine at times.