It's not a little secret that people don't know if they workout with kettlebells...but kettlebell workouts amazingly increase core strength. I'm in the home stretch of my bikini transformation, and I can now hold a plank for several seconds and for several times. I can do 4 pull ups now unassisted! It's amazing. Doing pull ups may not be everybody's desire, but I have wanted to be able to do pull ups for a long time without any assistance. To be able to pull my body weight up to clear my chin is truly amazing, since months ago I couldn't even do 1/2 of one.
I hope that kettlebell becomes mainstream, because I think it will cut down on how long people spend in the gym working out, how much strength they will increase, and how nice it transforms the body without looking bulky.