Any OS,no matter how secure it may be is useless without sound and hardware graphics acceleration.
For a desktop, sure. Just because people love making two changes to FreeBSD and releasing it under catchy names like FreeSBIE, DesktopBSD and DragonflyBSD, doesn't mean they have changed from a server OS into a desktop OS (or even a unique distro.)
I really wish these people would stick to forking Linux distros like they're used to. We only have ~200 of those so far ... come on guys, we need more!
That said, the work you put into turning FreeBSD into a desktop OS pays off in terms of stability in the long run. But it really, really is a pain in the ass, even with nVidia + HDA. The most recent final version of FreeBSD (6.2) won't run my 8800 without binary drivers (which aren't available for 64-bit, thanks nVidia), my HDA soundchip without extra drivers downloaded from a dev's homepage, or my NV ethernet card without adding the ID to the kernel module and recompiling it. It makes a nice text-console out of the box, though.
And ATI stuff doesn't really even work well with Linux. I hear nonstop complaints about fglrx, radeon, radeonhd, ati, etc etc Xorg drivers. You owe it to yourself to pick up a cheap nVidia card (or an Intel one when they finally offer them non-integrated) if you want to use X11.
AMD put up a good PR front with their bullshit "we'll release our card specs publicly" line. A year later and we have mode-setting information only -- great for cloning VESA2, not for much else. Yet everyone for some reason thinks they're OSS friendly now.