Nixpkgs has more and newer packages than the aur.
The initial time to get shit done is longer; you can't simply make install
, but honestly you shouldn't have been doing so on arch anyway.
Making your own derivation is much easier than making your own PKGBUILD and should be considered in those terms because you're not just shoving some binary into /usr/bin for it to explode later when glibc updates.
When things fuck up, reverting to your previous config is at worst a reboot away.
I have much less time than I used to, so moving from arch to Nixos has prevented the time otherwise wasted in an arch-chroot trying to fix issues like the kernel upgrading past what the zfs-dkms supports.
If you're using specialised proprietary tools, working them in with Nix can be an absolute nightmare, but I use a debian container for them.
Man if I was concerned about sinking the time to make a configuration for the compositor with a bus factor of 1 man-child, and a toxic community; I can't imagine anybody investing the time to make a compositor is going to want to hitch themselves to that cart.
The compositor is really solid and makes for a great user experience but I'll be fucked if every word vaxry writes doesn't make me want to move to sway or niri.