I have a couple of friends who are into Zumba. And they have nothing but great things to say about the exercise. I am even planning to give it a try anytime soon. Zumba is a great weight loss regimen because the dance aspect incorporates a lot of fun in exercise. And for me, the element of fun is important when choosing a weight loss activity as I am more likely to stick to it. I don't want to do something that just plainly bores and exhausts me.
As to how effective it is, that really depends on the length and intensity of your workout. There is a lot of movement to it, and if you are actually working hard (and sweating), then you are burning off calories. One thing I could suggest to even enhance the weight loss results of Zumba is to mix it up with other activities. For example, you can do zumba a few times a week as your cardio exercise, then supplement it with some weight or strenght training on other days. It's been shown time and time again that individuals who supplement cardio lose weight faster than those who do cardio alone.
I've just started going to Zumba in the past week because I'm trying to mix things up a bit. I usually do BodyCombat and CXWorx a few times a week, but now I'm adding in BodyPump and Zumba. I've avoided Zumba in the past because dance classes make me feel silly, but it really is a lot of fun.
karaheissman is so right about the effectiveness of Zumba (or really any workout). The class I took last night was a few minutes longer and a bit tougher than the one I took last Wednesday. According to the readout on my FuelBand (which may or may not be accurate) I burned significantly more calories during last night's class.
Haven't done it myself as an exercise but have for fun and it's pretty good! It is another exercise that you could get and do at home which is why I would really like to try get something and try it out.
My cousin's wife started around September last year and has lost an incredible amount of weight. They got married last week so I believe that is why she wanted to lose the weight. The difference it has made to her is just unbelievable. I can't say how much she lost because I'm not sure but it definitely worked for her. She has even been promoted as an instructor to the classes she goes too.