As a tenured FreeBSD noob and Ubuntu addict, I have a foot in both camps. IMO the OP is attempting to compare rosaceous pomes with citrus hesperidia when he asks about DesktopBSD as a "contender" to Ubuntu. Presumably the OP assumes the BSD projects care about market share of desktop systems. From hanging around the FreeBSD mailing lists, I can tell you that most BSD users (and I include developers in this) do not care which operating system you use. You should have seen the flames loosed upon a poor noobie recently who had the temerity to ask "why should I use BSD, then?"
The FreeBSD developer focus seems to be more "creating a system we like" than "creating a system everyone likes". It's a meme that pervades the FreeBSD community. Some of the more vocal FreeBSD users proudly proclaim that the best of all worlds is FreeBSD for servers and Ubuntu for desktops. (That's a great combination, by the way. I use it myself.) Of course, just because FreeBSD is this way doesn't mean DesktopBSD is, but since it's a fork of FreeBSD I'd bet my lunch money on it.
Speaking of DesktopBSD, I have recently been trying to decide between DesktopBSD, PC-BSD and DragonflyBSD for my BSD desktop slice. From what I can tell, Dragonfly looks the ugliest but the best engineered, and DesktopBSD is the prettiest - yes, KDE, but no-one said you can't install Gnome. A good rule of thumb for installing BSDs is: if you're not prepared to do some work, don't install a BSD. ;)
I've been having problems with using DesktopBSD in a VMware Server. It works fairly well but the file system is a bit unstable. One day I had to run fsck manually, twice. All I was doing was a regular ports upgrade. No way that should crash the file system. Either something about DesktopBSD doesn't like VMware Server, or they've somehow managed to make their UFS code unstable.
Most likely the flaw is a PEBKAC in the system. Does everyone have stability problems with VMware Server + DesktopBSD, or is it me?