Sometimes when I work the front desk at my local yoga studio, there's a class that only has one or two students signed up. If the teacher doesn't want to cancel, the class ends up being much like a private lesson for the students, since they get a lot of personalized attention and better access to their teacher.
I especially think a small class is the perfect place for a beginner in any type of exercise class to learn, since you can ask questions, explain your skill level, and receive a lot more help when you are one of only a few in the class.
Occasionally, however, a new student will hesitate to sign up if they see the class is almost empty. I can understand not wanting all the attention on you when you are a new student — I've been relieved that a class is big because it meant that I could set up my spot in what I think is the most inconspicuous place, but in general I'm excited that I get the semi-private lesson without the price of one. What about you? Whether it's yoga, Pilates, or spin, do you like the energy and anonymity of a larger class, or do you welcome the personalized attention of a small one?