I have a pair of Clubbells and unfortunately, I only use them about once or twice a month. I have so many other things going on.
They offer a good challenge for your grip strength and will improve your shoulder flexibility.
The only downside is that they do very little to strengthen your hips. They have tried to overcome this by adding a lot of full squats into the exercises, but even with two 15 pounders, it's still like squatting 30 pounds. While it is much harder on your grip and wrists, your hips don't know the difference.
I would recommend getting the video first to see if this type of thing is for you.
In general, I try to mix clubbells with sprinting, because they tax opposite muscle groups. I find that doing clubbells and kettlebells or rings concurrently is overload on my grip and tends to decrease the quality of my workouts. As a result, I tend to use the kettlebells and rings a lot, and the clubs very seldom.
Leverage lifting is cool though and it will appeal to a lot of people. There is also a cool family of exercises called casts that are pretty interesting.
Power Athletes Magazine- www.powerathletesmag.com