As a long-time Gentoo user, as well as the originator of the kernel seed idea, I can safely say that I like Funtoo a lot more than Gentoo.
Firstly, they bought my web site. What's not to love about that? :)
Seriously. The first thing I noticed and loved right off the bat was the git portage tree. Not only is it quicker and less taxing on an internet connection best described as crappy, it precludes the need for downloading portage to expand it where it belongs. Just open the stage-3, and tell it to emerge --sync. Viola! Instant portage tree where none existed before. When I ran into some corruption due to flaky kernel reiserfs drivers, I had to delete the portage tree a few times due to corruption. With git portage, not a problem.
I can't really comment on it being more stable than Gentoo, because I've never really had stability problems with either distro.
I also like that when I start it in CLI, the screen doesn't blank for login. I hate, hate, hate that about Gentoo! How can you possibly troubleshoot boot time issues if the screen blanks and takes away your error messages? Sure, it can be changed, but I don't understand why the default should hide boot messages and possible errors. No computer is perfect, and things happen. And sometimes, the log doesn't get the info, either.