The major one was packages never being marked as stable. There was a file you could add packages to in order to allow unstable versions, but it just kept getting longer and longer. If I wanted long term stability, I'd use Debian. For desktops and workstations, I expect things to be "fresh" where each distro has their own tastes for fresh, but certainly measured in months. (I switched to Ubuntu because I knew I'd get fresh Gnome, at a time when there were good system enhancements like NetworkManager.)
A quick check on http://packages.gentoo.org shows that no version of Gnome 3 appears to be marked stable. For the software package I am an author of, the most recent version marked stable was released 13 months ago and there have been 10 releases since! LibreOffice does seem to be an up to date version, as does emacs.
One area when Gentoo shines are the docs - they are very very good. I did try Arch a while back and ended up in a maze of using the wrong one out of official and unofficial documentation.