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.