I've been using it for 6 years now. Whether it's ready for YOUR desktop or not depends on you. Is Windows ready for the desktop? I would say "no" because it has a list of flaws that stop me using it. Being closed source is a pretty serious one for starters. There's no central software repository, you need driver disks for hardware, scripting is poor, it's got that registry thing, is suffers from bit-rot, viruses, spyware, adware... I could go on but as I'm about to say, it's pointless.
Lists of faults, blanket statements and generalising about which OS is ready or not is utterly pointless. They all have their faults and strong points. They are all desktop-ready for some people and they are all not desktop-ready for others.
Want to see if Linux is ready for your desktop? Try it out. You only have the cost of a blank CD to lose.