I run FreeBSD CURRENT on my MacBook Pro with a light tiling window manager. It is not as featured as Linux but it does run decently. Wireless configuration is done through editing wpa_supplicant.conf and restarting netif, suspend/resume don't work correctly, I haven't yet configured my audio to switch output from either the headphones or the speakers without having to edit /boot/device.hints and restarting, and a handful other things, for example. On the other hand, 9.0-CURRENT has included many new drivers for things like the Apple touchpad (atp(4)). Support for desktop use is slow, but it isn't ignored.
I would highly recommend you scrutinize your hardware compatibility before committing to an install on a desktop or laptop system.
I used PC-BSD (which kind of is to FreeBSD what Ubuntu is to Debian) for a while on my laptop. I really liked the system as a whole, but I had some issues with wireless support, and found KDE a bit sluggish (very low RAM on my laptop). But it's certainly worth a try - if you can get everything to work right, it's a very nice system.