I've been on a kettlebell kick and have been using them more than usual lately. I like kettlebells for several reasons:
a) They teach you to explode through the hips, which is possible the single most important factor in all athletic endeavors. Explosive hip drive is something a lot of athletes lack and can have a hard time learning through traditional barbell lifts. Not to mention, the kettlebell version of the classic olympic lifts (clean, snatch, jerk) is much easier to learn. Pretty much every kettlebell exercise out there is a full body lift, which if you haven't learned by know, is a good thing.
b) They are great for conditioning OR power development. As far as conditioning goes (they're tremendous for power/anaerobic endurance, which is they energy system primarly used is basketball), there is many ways to train for power/anaerobic endurance (hill sprints, stair sprints, killers/suicides, etc.), but kettlebells can be much easier on the joints.
c) You can train pretty much anywhere with a kettlebell (especially outside) versus traditional gym equipment.
d) I would say it's hard to find an exercise that mimics the vertical jump better than the kettlebell swing.
Now, after saying all that....Kettlebells are just a tool. They are not the magic training equipment that many make them out to be. You'd be a fool to use only kettlebells in your training. But, they are a great instrument and if you can afford them, why not? For beginners, they recommend men start out with a 35 lbs. kettlebell and women 15 to 25 lbs. It will seem much heavier than 35 lbs though. There are a lot of great sites to order them through and they are also at places like Dick's Sporting Goods and Sports Authority.
Here are some great articles on how to use kettlebells for power and explosiveness:
How to Combine Kettlebells and Bands for Explosive Sports Performance
How to Improve Your Vertical Jump With Kettlebell Training ?