I went to my first class last week - it was rubbish! They played really irritating new age 'whale type' music and it was so slow - didn't even hurt the next day which is my indication that something was worth doing (no pain no gain and all that!). I found it all pretty dull - each to their own though - you might love it! Give me an aerobics class any day - at least you feel like you've done something afterwards.
Its basically a whole load of various stretches that you do while focusing on your 'core' muscles and breathing - a lot of lying on the floor is involved (which is good if you fancy a nap!) - ooh and balancing on one leg!
Hope you enjoy it more than me!
MM x