Not a guru, but I've used it for a while. Both as desktop and server. My main gripe is that FreeBSD doesn't have a reliable filesystem. FreeBSD still dies pretty horribly after a few hard crashes (power loss, whatever).

fsck? In 2008? No thanks. Messages about possibly corrupted inodes? How should that be my problem? I can't stress this enough, one day you will wake up and FreeBSD will refuse to boot. And that day will, by Murphy's Law, be one of those days where you have to get an incredible amount of real work done.

I'm a big fan of FreeBSD, ports, and the whole "do it right" and "proper documentation" philosophy. But until they get journalling right you should probably stay away.

(also: upgrading from FreeBSD 6.x to 6.(x+1) is incredibly painful. I don't think upgrading a 7.x system is going to be much easier. Reinstalling FreeBSD gets old fast, so you'll probably just shrug and stick with whatever version you already have)