Substantially worse in my experience. They build the whole OS in CI which is slow and unreliable, and as a result it can take 2+ days for updates that other distros have out in under an hour. You can try mix packages from smash or unstable builds but for stuff like kernels that’s not simple.

The quantitative data we have shows that NixOS is fresher than other distros in general by a significant margin.

See https://repology.org/repositories/graphs

If you pick a specific random package update, nixpkgs often has that update months to years before other distros.

If you pick a specific CVE, nixpkgs usually is better with the exception of embargoed ones, where Ubuntu, Fedora, etc get to prepare their patched packages ahead of time.

> They build the whole OS in CI

As opposed to only building a part of the OS?