I tried it about a year ago and I don't know it did not convince me. Yeah it might be great for some niche developer oriented needs or deployment but for a normal OS usage, meh. I kind of see it as a current hype, just like crypto/NFT before, and AI now. For normal everyday usage I find openSUSE Tumblweed much more suitable and much more widely applicable.
What's the update process like? Do you have to reconfigure every configuration myself on update? I see this stuff about declaring packages and having multiple versions of stuff, but I don't get how it's sustainable unless you're on top of managing packages yourself. Like what if I have a version of network-manager and program-x that hasn't been updated in over a year that requires an old version of network-manager. Then that program gets updated, asking for the newest network-manager dependency meaning I have two instances of network-manager. Then there are other programs that are looking for a more up to date version of network-manager but not the bleeding edge one. That seems like it'll lead to a sort of quasy digital hoarding. And if you're on NixOS long enough you're just destined to run into dependency hell. Does Nix do anything to ward that off?