I haven't but I think they look like fun and the theory behind them is solid in terms of building functional strength and fitness that is useable and valuable every day instead of just making a "pretty body". (6 pack abs may look nice to some but often mask a weak core that is overtrained in one area and undertrained in others. It doesn't really help your stability or ability to react or move quickly for instance.) There was a gym here that opened with some kettle bell classes awhile back and I looked into them a bit having not ever heard of them. Didn't end up going because if I liked it on the free trial offer, I wouldn't have been able to afford the membership and I just like my power yoga anyway!
I'd say give 'em a try and see what you think! But yes pay attention to alignment and form as those kinds of movements done with weights can be potentially injurious if not done properly. (although that's pretty much true of any exercise including yoga!) Do you have a mirror you can work in front of? Often what we "feel" we are doing is different than what we can "see".