I switched my workstation over to NixOS ~6 weeks ago and it's been really good, I'm a total convert. The thing that really got me over the hump was entirely configuring it using Claude Code.
One unexpected benefit is that both my workstation and my backup laptop have the same setup, so I can run updates on the scratch box before doing my workstation. I decided to run the "latest" rather than 25.11 release, so it's nice to test before I apply (I hit a GDM issue a few weeks ago that left me at a black screen; but not a huge deal, just select the "previous" option in the grub screen).
I've got everything to parity with what I had on my previous Ubuntu workstation. I had anticipated issues with some software that isn't packaged (but NixOS packages a LOT), but that wasn't an issue. Claude was able to do all those things no problem.
The biggest tricky bit was with my vim setup; I've been using AstroVIM and trying to get away from managing my own vim setup. You can't, AFAICT, just apply astrovim in NixOS. So I described the vim setup I wanted to Claude Code, and I now have a ~700 line config that implements everything I wanted: LSP, TreeSitter, a small variety of other things. Unlike Astro/Lunar, where tweaks you want to make are buried in some set of files in this whole giant distro, it is all encoded in this one "neovim.nix" file.
I also set up home-manager and SOPS and so far that has been working just great! I now have home directory settings that are replicated across 2 machines.
I'm still really only using it on one machine, so we'll see how it gets more complicated if I start running it on some servers.