I am an avid fitness guy and have been for some time. I compete in Adventure Races (kayaking, trail running, mountain biking, orienteeting, etc.) and have enjoyed weight training using traditional bodybuilding routines for years. For my races I obviously incorporate some endurance training into my weekly routines such as running and biking.
Over the past six months, I have added CrossFit to my regimen. I perform on average two crossfit workouts a week. As some memebrs noted previously, some workouts are easier than others, but most of them come down to how hard you can push yourself. If you do them right you will be gasping for air and thoroughly exhausted. I firmly belive my weight training has helped me significantly with CrossFit, as I have been able to keep up (for the most part) with folks that do CrossFit entirely. These workouts are designed to be functional strength training workouts that will improve your strength in the real world (e.g., military personnel, police, fire, etc.). One example, is I completed a workout called "Fran" on Saturday morning which consists of three sets of barbell thrusters (95 lb barbell) supersetted with pull-ups with these rep counts 21, 15, 9. This workout took me just under 7 minutes, but kicked my @$$.
In the end, I think it comes down to what your ultimate goals are. If you are simply looking to get big, then stick with traditional bodybuilding routines. If you are looking to increase your overall strength, endurance, and get ripped then crossfit myight be for you. I prefer a blend of the workouts and have been very happy with the results. Hope this helps. If you want to learn more, here's a link to my friends CrossFit gym:
http://crossfitsweatshop.com/