Hi 心花花,
I have tried 工聯會 yoga before at 3 different centre : TST, Causeway Bay and Shau Kei Wan
The yoga class there is cheap, however, you have to find a good instructor. Some instructor just waiting your time as doing very very simple yoga exercise and just teach you few 式子 per class. If you never play yoga before, 工聯會 is good. But if you want to continue the yoga exercise, you better join other yoga centre as 工聯會 one is just elemtentary class only. They don't have intermediate or advance class for you to upgrade your skill.
Ms Chu of TST and Causeway Centre is good. Don't try the Shau Kei Wan one.