I have the X1 Extreme since December. Running Ubuntu 18.04. My experience with it was in short - "the worst possible ThinkPad that I had in 15 years" - and I had 8 ThinkPads.

Maybe I am unlucky. I bought it because I finally wanted a 15" screen with a centred keyboard, i.e. without the num-pad, because uncentered for touch typers is really really weird. It started that in order to get Linux running I had to switch the graphics card to discrete mode, at least this is what I found on Internet. This bricked the machine and according to the Lenovo support thread I was far from alone [0]! Luckily I had on-site 24h support, so called. They were able to come only after a week... With the wrong board... With travels in between I had in total to wait for 1 month to make the machine work.

Now it works and I am using it and trying to accept it.

- It is extremely loud! BIOS updates made it better as of lately and I got a bit more used to it.

- It gets extremely hot. So hot that actually typing on it gets uncomfortable.

- I am not able to do any meaningful work for more than 3 hours on battery. With my last X25 with 2 batteries I was able to work a whole day!

- The screen is like a mirror! I found a workaround by trying to work as much as possible with white background.

- And finally, but this is probably more the fault of Ubuntu/Gnome/nVidia - it is the laggiest experience ever! I mean, I am working most of the time in a terminal! Typing on the terminal is so laggy, that I do not even remember back to 1995 when I was starting using Linux to have such a laggy experience. Come on, this is supposed to be the most powerfull machine that I ever had?!

- Using external screen is possible only when switching ot nVidia. When using Intel graphics card (to prolong battery life) you cannot switch on external screen.

- Another, but probably this is Gnome/Ubunut/nVidia annoying thing is, that as soon as I lock the screen in Gnome, the fan starts turning like hell and the temperature rises! Come on, is Gnome screensaver mining bitcoins or what? I mean, I configured it to just turn off the screen when I lock it! And instead of saving energy it is heating the planet!

By now I spend so much time trying to configure, update and whatever that I am really tired of it. I mean, I have work to do! I am trying to prepare to go to NixOS, because I heard from some people that they got it configured to be usable. Preparing for this slowly, when I can dedicate time.

It's not all bad though. There are some positive things:

- I like the physical build quality. It feels solid and sturdy.

- The screen (I have the 3840x2160 resolution) brightness, resolution and colors are really good. To watch photographs or to see movies. Unfortunately working on text is only possible with white screen. Otherwise it is like a mirror. It would even be possible to work outside, but you need to have electricity, the battery life is horrible.

- I like the keyboard. The touch depths is nice and I have the impression that it is a bit more distinctive than on the prior models that I had (X25 and T450s).

- The CPU power is more than enough for me.

[0] - https://forums.lenovo.com/t5/ThinkPad-X-Series-Laptops/Anoth...

EDIT: Typo, s/X24/X25/