I haven't tried Bryan Kest, but I do like Rodney Yee's and have quite a few of his Yoga tapes. For me at first he came off being a bit odd, but his style of teaching Yoga really won me over. His Power Yoga is pretty tough, it took me, I think three weeks of doing it two times a week, to really get the hang of it. It's fast, so you got to really know your yoga poses and form, he goes over some of the trickier moves it with you, but it's more of a check list, then how to do it. But most of the workout, a pose is spoken everyone goes into it for about 2 seconds, and then another pose is spoken, the sun salutes are very quick. The first few times I made it threw without screwing up, I burned a little over 300 calories in that hour, and my body felt pretty well worked, as most of the poses were advance, and you really worked your arms in a lot of the poses as you continue to step in one only to push your upper body up to be in a totally different one the next second. I love it, and even take a Power Yoga class once a week, but do know all the standard Yoga poses by heart before trying Power Yoga. As most Power Yoga videos/classes assume you know, how to do the sun salutes, cobra, warrior pose, dog, cat, before you put the workout in the DVD player.
HTH,
Kit