I attended one of Pavel Tsatsouline's seminars several years ago in St. Paul, MN when I resided there...and before they were so expensive. I think he's pretty fair about the use/pros/cons of both free weights and kettlebells. He is very straighforward about the high chance for injury with kettlebells if proper technique is not utilized. I have witnessed a number of people execute kettlebell exercises with ridiculously horrible form and quite a few have dropped the idea/exercise entirely because the workouts are very demanding if done properly.
I think Mike's post above is accurate. If you want to maintain a physique significantly different than that of a 'bodybuilder', kettlebells will greatly assist but they are an excellent supplement to a weightlifting routine, again, provided that execution is near perfect.
I'd rather perfrom regular barbell cleans than kettlebell lift/clean repetitions. Having utilized both, the barbell was more intense and I was easily breathing just as hard after each set.
