One of my readers commented that they didn't realize that I had bought and started using Kettlebells. I bought one 35 lbs 'bell while I was in Minden, NV this past June. I've worked with it on-and-off since then. I've been traveling mostly by truck since then so I've been able to bring with with me wherever I've went.
So far, I really like it. After all, I'm stil using them quite a bit. Since it's a single, solid chunk of iron, it's pretty easy to throw into a truck and not worry about breaking or losing key parts. It's also more compact than a comparable dumbbell. I really like how much of the methodolgy around using them focuses on strengthening the muscles that move and stabilize the shoulders and the hips primarily. All of these joints are key to just about every powerful movement that you do.
The two exercises that I use more than all of the others. The first is the ubiquitous swing. The second is one I adapted to KB use, called the woodchopper. I'll tackle that one first. Originally, this was intended for use with a light dumbbell. Since I didn't have one of those with me at the time, I used a stone. From there, it was pretty natural to try it with a Kettlebell. I modified the form a little bit from the way that I learned, when i saw this picture. Instead of starting with over the opposite shoulder, I started with the weight overhead (but not too far back, behind the head). That puts a lot of the work on the shoulders. As with any exercise, I don't let the weight drop down. Instead, I control it, bringing behind the knee. That fries the obliques a lot more. Reserve going fast for bringing the weight back to the starting position.
Everyone who uses Kettlebells uses the swing. It's a great exercise for the muscles that, in any way, connect to the hips. For once, I don't know what else to say about them that hasn't been said. I use them, I like them, and I don't see myself stopping any time soon.
The thing is with Kettlebells is that, with any fitnes craze, the hype runs amok from the reality. I like training with the 'bells but I don't think that they're as unique in their training effect as the KB-peddlers would have you believe. A huge part of what makes a kettlebell distinct from the other 'bells (dumb, bar) and machines is that they're awkward. Their weight, and therefore their center of gravity, is in front of your hand(s) and not on the sides. When you think about it, weights have gone in a direction of making them easier by making them less awkward. You lose a lot because you don't have to struggle to stabilize the weight like you would with a kettlebell.
Plus, it's not like you couldn't replicate this odd-ball center of graivity thing with dumbbells. When I was training at the Hilton's gym in Orlando, I did swings with a dumbbell by grabbing onto the weight rather than by the handle. It's not an exact replication of the Kettlebell, but it's more awkward for sure. Since I grab the ball of the KB, rather than the handle, when doing woodchoppers, the only difference that I notice is in the grip.
Overall, I see the option of owning the Kettlebell as purely personal. I have some very valid reasons for owning one, so they are practical for me. If you enjoy them, then by all means indulge. In my not-humble, non-expert opinion, they're very nice but not as necessary as some would have you believe.