Can anyone provide a comparison with Nix? I wonder if they considered working with the Nix developers, sharing is good for the ecosystem :)
I don't feel saying them as either bad or good compared to Nix. Until you try a system, there's little to say only from the theory.
We'll see how Ubuntu Core with snappy performs, and this question will be more relevant in a few months.
Nix is not perfect but certainly has a long story maintaining this kind of packaging.