Sumits Yoga combines the best of the best.  I have been to Bikram Yoga where you practice hot yoga with stretching type movements.  The focus there is on repetition and improving in practice.  I have also been to regular yoga where you can do more difficult types of moves.  Sumits Yoga is a great combination of the hot room concept with regular and complex yoga moves.  In addition, you do a bunch of pushups and situps in the room as well.  This would be like yoga on steriods.  In the end, you come out of the room feeling amazing!