See the resemblance?
XTR, Hayes discs, Lefty shock. I haven't changed much on it since I got it 5 years ago, other than regular maintenance (drivetrain, tires etc.), just a different seat, new pedals, third set of grips and I cut the bars down.
I wasn't sure about the disc brakes when I got the bike, but there's no other option with the Lefty. After riding with them, I love discs. I feel like I'm driving a sports car, fast into the corners and fast out.
The Lefty took a few rides to get used to, but once I got the air pressure dialed in... like butter. It can be a little disconcerting to look down and see only the one arm, but you shouldn't be looking straight down on the trail anyway. Performance wise, I think it steers better than a conventional shock.
I have ridden this bike all over, CO, UT and my own stomping grounds- the Kettle in WI and Palos here in IL. I can't imagine riding any thing else. I suppose at some point I'll go to full suspension, but for now Bill E. Goat is my steed of choice.