I've been doing Crossfit for about twelve months now. Incredible results. I can repeatedly jump on a box waist-high from a flat footed standing start. I can do at least five hand-stand push-ups. My run time and bodyfat has decreased while my overall strength has increased dramatically. I'm 46, former Marine, been working out/bodybuilding all my life.
Funny story. I walked into to gym at Camp Phoenix one Friday (I usually work out at Camp Eggers) and went to the squat rack after warming up. There were three young soldiers on the Smith machine next to the squat rack. They were doing squats with 135 lbs., on the Smith machine, touching butts to a bench. I loaded 135 on a bar on the squat rack, stepped under it, pressed the weight overhead, and did five deep overhead squats. The young soldiers immediately left. God I love Crossfit.