There’s a lot to like about Nix, including that packages are content-named, and that dependencies are tracked. There’s some crazy parts, like the fact that runtime dependencies are determined by scanning binaries for the content-names of Nix packages, but since a long content name is pretty much a unique thing, it sounds scary but is actually quite safe.
It also makes building very safe, if you have everything as packages.
One negative is that this only supports Unix-like systems (Linux, Mac OS X, FreeBSD). A lesser negative is that it introduces yet another language, the Nix expression language.
The NixOS Linux distribution is built around Nix, and Hydra is a Nix-based continuous build system.