As a triathlete, swimmer and kettlebell instructor, I can tell you, kettlebell training is truly one of the best forms of strength and conditioning I can think of. Some key elements of kettlebell training are:
Hip Flexibility - which is increases with swings, figure 8's, slingshots and snatches
Ability To Gererate Power- the ability to keep the hips neutral (like swimming), knees locked and driving (rooting) the heals into the ground
Shoulder Mobility- Hip positioning has a direct relationship to shoulder mobility. The more neutal the hips, the more the lats will be stretched out. The lats are responsible for shoulder flexion and extension, not the deltoids. Think of Overhead presses / Shoulder presses as "back" exercises and not shoulder exercises. To prove this, press a heavy kettlebell or dumbbell over head and hold it. Your back muscles (lats) and obliques will give out before your shoulder ever will.
Kettlebell training is metabolic conditioning or "met-con", meaning you will go into anaerobic threshold during high repitition lifts and the balistic movements of the workout. If you have any questions, please feel free to respond back.