I have been going a couple of weeks. It's the single most popular class where I go. This is what I have discovered. - you can work as hard or not as you want. The results will be based on that. The steps are fairly easy but fast. You can either just walk through them or really throw your hips into the moves. The dances are fast, but repetitive. Just trying to keep up the 1st few weeks I had a couple laughs and really sweated something crazy. I stood in the back and as long as you are moving it's ok. I'm still mostly walking through. But as they are becoming more familiar to me, I am concentrating more on moving my hips and not just my legs. I am trying to isolate my abdomen muscles and I can feel my stomach is sore the next day now. There's not much upper body going on. Mostly all lower body, hips, and stomach are used. I know it's cardio because my heartrate goes way up and I sweat so much.
I'm going to keep doing Zumba twice a week, because it's fun. It's good for my mood and I feel good when I'm dancing, sweating, and laughing. I look forward to it. But I'm also going to incorporate a more traditional workout 1 night a week. I miss really stretching and working my muscles.