Poliquin is putting out his version of the kettlebell. It's interesting to say the least.
I've used them for 2.5 years. They work the best for me. I've gotten bigger, stronger and in the best shape of my life using them. I've also avoided injuries that I used to get using dumbbell and barbells.
Are they the end all be all? For some yes, for some no. But if you do a heavy double kettlebells you won't think they suck.