Two gripes about FreeBSD so far.
Full Disclosure: I'm running FreeBSD 7 under VirtualBox 1.6.0 (recently rebranded under Sun).
1. It runs DOG slow in Gnome (technical term, indicating an overall qualitative analysis rather than an actual quantitative measurement; in the common vernacular, this could be termed "slower than molasses" etc).
2. No sound. No clue why. I'm guessing the VirtualBox emulated hardware is not fully supported by FreeBSD. I might drop back to 6.3 and see if that's better.
I always did like FreeBSD (well, when it works, that is).
EDIT: Changed "X-Windows" to "Gnome" for accuracy. I'm not really sure what I'm doing, but running plain X via "startx" is fast enough, but running the Gnome Window Manager on top of X-Windows via "gdm" is like, painfully slow.