Yes, today was my POWER YOGA!!! class. (Sorry, I really do have to type it out like that– that’s how I’ve been saying it in my head.) It was pretty good. I liked the fast-paced style, and it certainly got my heart rate up and made me all sweaty. Really, it was easier for me than the slow yoga; holding poses for long periods of time and deepening stretches is harder than only spending a few breaths in each one. I suppose it fills a niche for people who like their yoga with a side of cardio, though it’s nowhere near as intense as I practice my cardio and I wouldn’t like it as my only cardio.
I’m still having problems with my shivasana… the teacher used an unorthodox soundtrack of Led Zeppelin for the main part of the class, which was fine; for the end, though, she put on John Lennon’s Imagine as we laid there. Now, I know I’m in the minority on this, but Lennon makes me ragey because he’s held up as this peace-loving idol, yet managed to be abusive to just about every woman in his life. So yes, poor choice for me and I couldn’t get past that and relax into shivasana. My fault, not the teacher’s. :)
Running While Fat 
It’s funny. I’ve heard a lot of people talk about power yoga/other cardio and come to the same conclusion you did — that it’s cardio but not uber cardio. For me, for whatever reason, I’ve always found an intense vinyasa practice to be the cardio-est thing I do. :)