This picture sums up the experience well. You put your mountain bike on a chairlift, then ride it down a trail and try to avoid catastrophe.
I borrowed a friend's bike, which wasn't built or fully configured for this purpose, which slowed my speeds considerably. Downhill bikes have forks with 8" of suspension travel, cushy rear suspensions, and tires looking like they belong on motorcycles.
Still, the experience was excellent -- what's not to like with endless downhill? I kept having to remind myself that this wasn't like skiing, where a minor fall is no big deal. Here any fall, however slight, had the potential to break an arm or leg. Lots of full-face helmets and shin, knee and elbow guards on those who appeared more expert. Also, there was a system of access roads where the pickup truck with a stretcher in the back could evacuate an injured rider.
Another way to get up on the mountain and proclaim stoke!