The 26in version of Conti's Ultra Gatorskin is new for 2006. It's a lightweight skinwall like the 700C version that's done well in past tests.
Since it's high pressure and narrow - just 28mm - it feels more like a 700C training tyre than a mountain bike slick: it's harder, less bump absorbing, and faster. In fact, it's one of the fastest 26in tyres I've ridden. Grip is fine and puncture protection is good for such a light tyre.
The Kevlar belt resists sharp objects well: I've had one puncture in about 1,000 miles on a 700C version. The sidewalls are protected by 'DuraSkin', a synthetic-mesh layer.
This should help against slashes but offers little resistance to piercing. Despite the wire bead, the Gatorskin is very light for a 26in slick. That surely means less rubber so we'd expect mileage-life to be lower. But it's cheap enough to factor in the price of a spare.