I LOVE zumba! I've been going 1 or 2 times a week for over a year now. I am very coordinated and have taken salsa lessons before, so I come by it easily. I am thinking of getting certified to teach next month. So, with my experience I have to say:
I have watched many new women come and go throughout the year. Everyone, and I mean everyone, looks and feels uncoordinated at first. It's okay. But, if you stick with it, it will get easier, I promise. One of the secrets is that we tend to do the same songs over and over. So, everyone else looks like they're getting it easier than you, but they've done it many times before. I have done some of the exact same routines for the whole year. If you just go into it with the attitude of having fun and moving, you will be successful. If you think you have to do everything perfectly, you'll probably quit. And, don't worry about how you look. Everyone else is so focused on how they look and feel, they don't have the energy to look at what you are doing!