Actually no, NixOS is probably easier to use than other Linuxes. It gets more difficult when you need to package something new that it doesn't have, then you have to know the Nix language and how nixpkgs work.
Interesting; when I tried it a while back it seemed like you needed to know the language to manage your configurations. Was that impression incorrect?
I may have tried it far enough back that I pretty much immediately encountered packages I wished it had and tried (and failed) to package it myself, though, and got the experience mixed up…
No, you're 100% correct. Despite the prosthelytization you'll get from many died-in-the-wool users who forgot what it was like in the beginning, in order to use NixOS effectively you either need to learn Nix, or be willing to spend a lot of time on IRC asking questions, which will end up with... you learning Nix. That's the reality. I think I spent something like 3 weeks porting my server configuration from Ubuntu to NixOS, by hand, piece by piece, many years ago. Admittedly I think we're better off than we were 7 years ago, but it's still not a grand slam. Even things like basic GUI installers that can set up your filesystem don't exist! Manually screwing with partition layouts to get volume encryption isn't easy to use at all, honestly.
There are an array of flaws with the tools but, despite that, they are unbelievable powerful and you can do things in NixOS you can't dream of doing elsewhere, and it makes things like using OpenZFS or whatever pretty easy and simple. And it makes some thing far more difficult than that, nearly trivial. But only once you know what you're doing. But that's just the reality: it's an extremely powerful tool that has many rough edges. Saying it's "the easiest distro to use" is a complete joke, and I wish fellow NixOS users didn't have some weird propensity to practically lie about how good it is on that front. I say this as someone who has been a NixOS developer and user for like, ~7 years and who apparently(?!) has over 1,000 commits to the tree now, too. Trying to actually sit down at a terminal and sell unconvinced people on it opened my eyes quite a bit. It's good, but lying about what it is and isn't is a good way to burn peoples faith.
I don't think what you said necessarily contradicts what I said.
NixOS is easy to use as long as as what you're trying to do is contained within the configuration, then set up is pretty much just editing that configuration file (which essentially is just series of dictionaries and lists). I wouldn't for example have with installing NixOS for my grandparents.
If you want to do something that's not covered then you'll have to learn Nix, and that part is indeed hard, because it's like configuring linux through use of saltstack/chef/puppet/ansible through a functional language (which many people don't have experience with), but as you said it pays off.
I think the hardest part is the paradigm shift where everything you do is no longer imperative but declarative. It also doesn't help that documentation is always behind what nixpkgs can do and Nix functionality would cover multiple books.
in my hardware-configuration.nix. tank/media is defined as using a legacy mount-point or whatever the ZFS terminology is. Done.
ETA: I mean, I had to do all the gruntwork to get the pool built, yeah. But once it was defined, getting it mounted and all the kernel bits and bobs set was trivial like that.