I bought a set of 10 classes (admittedly missed one due to illness) and went to the classes in the mornings twice a week. I loved the times of the morning classes - at 7.15, they gave me enough time to do an hour's worth of exercise and still get to work in loads of time.
The setting for the classes is the beautiful Jubilee Hall in Covent Garden. This gym is amazingly nice! The changing facilities are really good and the showers were usually ok - often no queuing, temperature usually constant and lots of room in the cubicles.
The classes were great - really energy and I definitely feel like I got the best out of my hour's worth of work. The instructors were really friendly but still really pushed you to try your hardest. I definitely saw results in the time I was there. The full price is also reasonable - it's more expensive than my local council run gym which is why I'm now there but I know many people who pay as much, if not more, than the subscription to here.
Overall, I would highly recommend.