I've been using Linux for nearly 30 years and I recently noped out of NixOS. It's a great concept, but I'm old and I don't want to spend the rest of my days configuring stuff just to get to where I would be in 30 minutes on a less rigorously designed distro.
That is, until your distro releases an update and you're like "what do you mean the update failed? So does that mean the update script rolled the changes back?" and then you find out your entire system is in a half updated state and you need to clean install
That's saved my ass soooo many times. I now screw with X or Wayland to my hearts content, change 2-3-10 things at a time. ohh something didn't work? reboot!
It's not even fully immutable, but it has a lot of the protections of it. The declaritive part is pretty hot and the package system is expansive and extremely safe.
it's also really nice to be able to commit new changes without rebooting.
And then you'll wonder why the game that used to run in Wine doesn't run anymore
Not only that, programs just break by themselves. LocalSend broke because some deps broke. I use versions that I've verified to work. Being able to revert and just use my computer is a godsend.
openSUSE Tumbleweed made me a full Linux convert. I have "messed up" quite a few times, since I'm still very much a Linux noob, but openSUSE gave me that real confidence in my setup that I now boot into Windows only for a program or game that won't work with what I am needing at the moment, which is almost 10% of the time. Modding games is a hobby, and that's still not as easy as it is in Windows. Come on Nexus Mods, you can do it! :'-)
I'm in an interesting place because I installed tumbleweed as a server. At some point there was a change to networking and when I updated, networking didn't work anymore, so I had to roll back to just before the update. I don't want to start from scratch, and I don't want to either bring a screen to it and troubleshoot what's going on again. I tried in the past, and after a few hours of getting nothing (everything should be fine, it just doesn't send or receive anything), I rolled it back and walked away. I have a feeling I just need to run yast and reconfigure there after updating, I just don't want to go through the effort of fixing it because it still runs fine.
For me, it felt like old times. Bringing up slackware, then bringing up redhat, then fighting in laptop Nvidia and AMD drivers. I was scary how much of my existing knowledge was useless though. If you install it by the book, you can't even run a linked library.
I spent a couple of hundred hours learning how to configure it. I've been running it for around a year and a half. I'm still sub-par. First time around, 23.11, I installed home-manager as a flake. I got it up and running in a couple of hours, but managed to wedge myself when it was time for updates. I had written just enough weird nix language to make my configs not work in 24.05. I could get the OS to come up, but not home-manager. I started fresh, taking old configs item by item and re-implemented them via the docs fresh.
When I got a new laptop, I booted off the USB, copied my home folder and grabbed configuration.nix and home.nix and it all just magically worked.
That said, NGL, 25.05 has me a bit worried :) But at least I don't have to fight Wayland this time.
That's way, way more time and effort than I'm willing to waste on getting my computer up and running, and I still fail to see any real benefit over copying my Arch home folder and reinstalling what I need from Pacman/AUR. If I had to set up dozens of computers at a time then yes, absolutely, Nix would be perfect!
It's actually easier than that, but I know what you mean. Yesterday I installed arch on a new laptop, after two years of NixOS. I think I might swich the desktop too.