I've seen several posts about these recently. Are they weighted balls with a handle on them? Are there workouts out designed just for them? Are they intense?
KBs have a great cross over training effect for a wide variety of sports to enhance strength, power, flexibility, endurance, speed, and coordination just to name a few of the many applications. I can tell you that for me, nothing has gotten me into better physical condition than kettlebells. They train me the way I want to be trained. I do still use traditional weights as well, but I will always keep kettlebells in my rotation. They just work.