I joined Curves at the end of March. I like it a lot. I am struggling to lose weight but it is my fault, not Curves. I know someone who lost a lot of weight going there.
I like it because you are in and out very quickly. The exercises are not that difficult but you are still getting a good workout. Also, it is not terribly expensive and they often have specials. I feel a lot better physically also since I have joined.