It's so kino. Incredibly hard to learn and much more to master, but much more powerful. Nothing beats easily modifying a derivation's source, or adding patches or build options or whatever you want.
I only use Gentoo for a small bit, so I can't comment on it, and I haven't used the other thing ever. I wish linux a culture similar to the bsds when it came to ports stuff. /usr/local is barely used if ever.