It's less than a month old, which makes me less confidant in it than I'd like. Gentoo, at
least, likes to leave a kernel marked as "testing" for 3 weeks to collect bug reports before
deciding what needs to be followed up on before marking it "stable". In general, this has more
to do with getting other packages updated for changes (e.g., /sys/block/* being symlinks) than
kernel bugs. Of course, these aren't something to complain to kernel developers about, but
neither can they be ignored when choosing a kernel version. For example, old versions of
x11-drm use flush_agp_mappings, which has been removed in 2.6.25, while newer versions of
x11-drm don't work for some people. So, if you happen to have particular hardware and
particular external module versions for it, you have to wait for stuff to happen that's
outside of the kernel process before you can switch to 2.6.25.
Regardless of the internal quality of a kernel release, there's the question of whether it
will trigger bugs in other packages. FWIW, Gentoo just released a 2.6.24-based kernel last
night, backporting at least one of the security fixes from 220.127.116.11.