- a language friendly as Haskell, so while fit for purpose definitively it's not well digested by most, also by various longtime NixOS users;
- an unclear direction, there are countless of "side projects" and no clear path, most are not even indexed in a wiki page so you just discover by accident interacting with someone else or after a search;
- a terrible documentation probably due to the lack of a clear direction stated above.
The biggest "mean install" is true, but it's not that much impacting in the real world, NixOS real purpose is AVOIDING containers in designing an infra, not being wrapped by them or wrapping them and true x86 zero-overhead virtualization does not exists. So far only IBM Power Systems with AiX seems to have something nearly-zero-overhead built-in in the (big)iron.
IMVO that's the main point: most people, NixOS devs included, fails to see a world different than the current one. A possible answer could be keeping up the evolution of zfs and mirror some IllumOS features so we can have light paravirtualization thanks to zones on zfs clones. But as per NixOS most people fails to see a different storage than the most common today, a relict model from the '80s (does anyone remember the infamous "zfs is a rampant layer violation" phrase?). A damn real modern system should be: a SINGLE application, yes, the OS as a framework, development environment who produce a running system live out of itself. A coupled package-manager/installer/storage, because those are effectively a unique thing so we do not need a network of symlinks or containers, we have a storage behind that simply expose needed software pieces together, also a system who manage in-memory stuff the same way. Zfs was the first step in this direction, with boot environments, clones, zones glued by the Image Package System, lacking the language for a proper system integration, unfortunately almost nobody have taken care of that. NixOS and Guix System offer another piece, the language to integrate package management, installers but they lack the storage integration to generate a unique new system model.
Rediscover IllumOS (OpenSolaris) would bridge the gap providing all needed piece to start a new kind of distro and infra management for a FLOSS world where there is no need of monsters to deploy simple infra and those simple tools could scale at monster level, killing the commercial IT model of the giants and given the humanity the desktop model, the "pioneering internet" of interconnected personal system model a new start.
The lack of independent universities, big labs, is probably the root cause but as always good things tend to happen anyway sooner or later, it's the interim the bad part.
Re: unclear direction - I have never encountered another ecosystem more prone than Nix is to have people (and startups) trying to build their own little technical/commercial/social fiefdoms around some specific idea that X is the One True Way to do Y. Fragmentation is pervasive and detrimental and one of the major reasons I'm moving away from the tech, second only to governance.
Haskell is so much worse with its custom operators.
So a vibrant community is now bad?
Also there where big improvements in the last years like freeform settings.
Try reading Debians Postgres Documentation and you get a sense what terrible doc is. Not only do they point to each withput instructions but they are also about 9.5 which is stone age old.
It's not bad experimenting, but a thing is experimenting and have a mainline with a clear path, another is having only experiments, mostly undocumented, hard to discover, and so on.
What most people want from a distro? Being rock solid and functional with the minimum effort for anything. NixOS offer that formally, well, stating it's legacy because Flakes are the future, but their are still not there, than NixOps/Disnix and so on, this does not play with this other etc etc etc. Essentially a generic user, not a developer, have hard time to craft a stable infra with stable tech and so most fear the change reducing the community to a nearly devs-only show and enterprise player show.
Debian docs in general aren't excellent but Debian is a well known dinosaurs so most of it's users already know it, there is no need to teach anything to most, those who do not know simply ask their side friend. NixOS while not new it's still unknown to many so it have to teach well from zero various people, who aren't interested in NixOS development itself but only in it's use, model, that will contribute with return of experience, translations, casual patches and no more. They might be seen as a burden to devs, but they are "the base" that grant any distro enough popularity to really thrive.
Ubuntu back than succeed over Debian because of that. They gives a sane, ready-to-work base. There is no need to a NixOS GUI installer or so, that's not a potential target, but there is a damn need to tell anyone "start with that, learn that, in 5 and 10 years it will be the same evolved properly" No one want to learn and relearn things.
NixOS and flakes are orthogonal. Flakes are not a replacement for NixOS, they are simply a _lockfile specification_, akin to your requirements.txt or Cargo.toml or such. NixOS is not legacy.
- a language friendly as Haskell, so while fit for purpose definitively it's not well digested by most, also by various longtime NixOS users;
- an unclear direction, there are countless of "side projects" and no clear path, most are not even indexed in a wiki page so you just discover by accident interacting with someone else or after a search;
- a terrible documentation probably due to the lack of a clear direction stated above.
The biggest "mean install" is true, but it's not that much impacting in the real world, NixOS real purpose is AVOIDING containers in designing an infra, not being wrapped by them or wrapping them and true x86 zero-overhead virtualization does not exists. So far only IBM Power Systems with AiX seems to have something nearly-zero-overhead built-in in the (big)iron.
IMVO that's the main point: most people, NixOS devs included, fails to see a world different than the current one. A possible answer could be keeping up the evolution of zfs and mirror some IllumOS features so we can have light paravirtualization thanks to zones on zfs clones. But as per NixOS most people fails to see a different storage than the most common today, a relict model from the '80s (does anyone remember the infamous "zfs is a rampant layer violation" phrase?). A damn real modern system should be: a SINGLE application, yes, the OS as a framework, development environment who produce a running system live out of itself. A coupled package-manager/installer/storage, because those are effectively a unique thing so we do not need a network of symlinks or containers, we have a storage behind that simply expose needed software pieces together, also a system who manage in-memory stuff the same way. Zfs was the first step in this direction, with boot environments, clones, zones glued by the Image Package System, lacking the language for a proper system integration, unfortunately almost nobody have taken care of that. NixOS and Guix System offer another piece, the language to integrate package management, installers but they lack the storage integration to generate a unique new system model.
Rediscover IllumOS (OpenSolaris) would bridge the gap providing all needed piece to start a new kind of distro and infra management for a FLOSS world where there is no need of monsters to deploy simple infra and those simple tools could scale at monster level, killing the commercial IT model of the giants and given the humanity the desktop model, the "pioneering internet" of interconnected personal system model a new start.
The lack of independent universities, big labs, is probably the root cause but as always good things tend to happen anyway sooner or later, it's the interim the bad part.