I've only been to one Zumba class so far, but the one class was great, and I signed up for a full 10-week session.
The instructor was wonderful, and the environment was *so* friendly - I was nervous going in, but everyone was smiling and happy, and the class was fantastic - everyone had a great time.
The room is comfortable, and unlike many fitness studios, doesn't have mirrors. While you need mirrors when you're doing free weights to ensure good form, for classes like Zumba and yoga (which is also offered here), you don't really need them, and it makes the studio feel more friendly.