To those complaining about compile times: Tinderbox and the GRP.
There are binary tarball repositories made from the tree by various people, many off whom are happy to make the binaries available. Indeed, these are quite commonly used when rescuing a system which some (normally new, but not always) user has managed to break by removing something critical.
The big thing about gentoo is the package manager (any of the three qualify). It makes keeping stuff working nicely easy, and is one of the most robust to rapidly changing packages installed when coupled with one of the maintenance tools. (Actually, the version of the package manager in the unstable tree doesn't even need the tool.)
For me, my use of gentoo is based on the fact that I found it ridiculously easy to break RPM, and when I started Ubuntu wasn't really on the scene, and we were still waiting for the Flying Pigs with Debian.