I like what Dr. Andy Galpin says, "concepts are few but methods are many." Essentially a kettlebell is just a piece of equipment there is nothing magical about it. That doesn't mean that there aren't some advantages and sometimes disadvantages over other pieces of equipment. The advantages are that they require a little bit more stabilization which tends to carry over into better real-world strength. Picking up awkward objects, lifting things overhead, etc. will become far easier from kettlebell training. Also fighters and athletes notice kettlebells tend to give them an edge over the competition as they are better at working against objects that want to go their own way.