Gentoo is a linux meta-distribution where new packages are compiled on your machine before they are installed. We chose Gentoo about three years ago because it was well documented and also the only one that supported our AMD 64bit machines.
In the last three years, we never felt the need to perform regular updates. However, yesterday I noticed that on one particular machine, the log files were getting very large. Switching to syslog-ng instead of the good-ol syslogd package seemed the right thing to do. However, since we never upgraded the platform, the view of the available packages, i.e. the portage tree on the host, was too old. Thus, the installation of syslog-ng failed. The portage tree needed to be upgraded. By the way, portage is Gentoo's installation framework.
Thus, I updated the portage tree by issuing a "emerge –sync" command. However, in the meantime the package description format had changed so that the version of portage on the host could not read the updated portage tree. It appeared as if the whole portage tree was corrupt. Thus, a chicken-and-egg situation emerged. I could not install the latest version of portage because my portage tree was unreadable by the current portage software.
Anyway, once I realized what was going on, I copied over an older version of the portage tree from a backup, installed a new version of portage and then updated to the latest portage tree.
Even after this relatively troublesome event, I still love Gentoo and the stability it provides. Our Linux systems just work without a reboot for years on end. The latest experience notwithstanding, it's usually very easy to install or update new packages.
More generally, dependency management is one of the key features of any serious software platform. For instance, Maven, a java build-tool, is becoming increasingly popular, imho mainly because it helps with dependency management.