I can't take the heat. I've got a couple friends who are really into it, but I get lightheaded after about 5 minutes in that temperature.
I prefer Iyengar yoga, which focuses more on holding the poses. It forces me to strengthen muscles that are unbalanced from the rest of my body. If you don't like the heat, see if you can find an Ashtanga or Power yoga class. These focus more on pose flow and deliver a butt-kicking workout.