I bounced off it two or three years ago after trying to get it running a basic GUI desktop environment by following a guide (IIRC an official one of some sort? It seemed legit, certainly) and after an hour or so of installing and faffing about was nowhere near having it working or even feeling like I might, after another hour, get there. Nothing seemed to work right or do what it was supposed to, troubleshooting was hard, and learning some new (and, at least initially, quite unpleasant) language just to configure this one package manager... ugh, no.
For reference I ran Gentoo on an IBM Thinkpad as my main computer for a few years in the oughts, among a bunch of other Linux work, so I, by necessity, at least kind of know what I'm doing with desktop Linux installation and config, from a fairly low level on up. At least that knowledge has proven highly transferable and, over and over again, relevant and useful. I didn't get the impression I was learning anything from NixOS other than how to make NixOS work, and I wasn't even making much headway at that.
For reference I ran Gentoo on an IBM Thinkpad as my main computer for a few years in the oughts, among a bunch of other Linux work, so I, by necessity, at least kind of know what I'm doing with desktop Linux installation and config, from a fairly low level on up. At least that knowledge has proven highly transferable and, over and over again, relevant and useful. I didn't get the impression I was learning anything from NixOS other than how to make NixOS work, and I wasn't even making much headway at that.