Hi Alice,
I am a member of Amore for several years. I find that they are good. They have a lot of classes and they are quite flexible, you can go to any of their branch to your convenience.
I've tried their areobics classes for low and high/low impact, very good cardio work out. Besides areobics, they oso have pilates, yoga, power yoga, kick boxing, step work etc. to enable you to choose from on your targeted area to work out.
If you want to see the effectiveness, I think at least you must go twice a week, best its three times a week, of cos must oso go with a sensible diet.