I've been using flakes for well over a year and there doesn't seem to be much discernible progress.
There is agreement in principle to carve out a store only Nix so the no-flakes crowd can build their own UI on it which is held by them as a pre-requisite to any stabilisation of flakes, along with some bad blood of it being announced by blog post. But it's slow because the project maintainer and chief flakes advocate doesn't want to adjust the project just so an alternative frontend specifically to avoid their view of an easier Nix should go ahead.
People are still working somewhat constructively towards this in 134, but because their goals feel fundamentally opposed, it seems likely to go on a while.
Consensus is hard but I'm glad to see people coming together on this. Really looking forward to seeing the new Nix command and flakes move forward (independently)
One of the things it adds over Nix's design is types (it grew out of early efforts to add gradual typing to Nix). It has a gradual typing system with 'contracts' for dealing with untyped code.
I have spent some time doing exercises and examples in it, first in Nix code and then translating it to Nickel. It feels very Nix-y, in the best way, and I think in the end it will be very nice to use.
Definitely check it out if you have thoughts about Nixlang and how it could be better! Development is very active and the maintainers seem quite appreciative of testing and feedback.
Really that's almost all of my issues with Nix[(pkgs|os)]. Nickel hopefully solves that quite well.. we just need it to work with Nix first, which is a big hurdle on its own.