It really depends (on amd64 support, for example). I saw massive
improvements over 5.1 when I installed it on a test machine. But the
subconcious tugging that it's really underoptimized (compared to 4.x)
remains.
Nevertheless, I have no choice but to use it - 4.x is getting no
significant development, and is starting to have problems with some
recent hardware, and dragonfly is not ready yet... (and still needs
support for the mentioned recent hardware).