I use mine with linux (Ubuntu Mate + xmonad) and so far I like it (as a disclaimer, the company bought it, not me personally).

What I did so far:

  - updated all the firmware to the latest (thunderbolt has a separate firmware)
  - bumblebee automatically disables the nvidia gpu on startup (i don't need the extra power or power draw)

I run in 1080p on the 4k screen, which is kind of sad, but the hidpi support just isn't there yet. Gnome3+ might have better support but can't replace the WM for xmonad in those variants.

I used to have the first XPS13 model with linux support officially from dell and this laptop is just as good and even better due to better hardware. Slightly larger and heavier but not an issue for me.

Palm detection support is ass and might have to look into it more as it's driving me crazy. There is also some firmware bug where the screen won't start after sleep.

With proper hidpi support and remaining firmware fixes from dell this will be a nice laptop even with linux.