I've been to Saravanaa Bhavan twice now. It has a huge reputation among my Indian friends as a premier south Indian vegetarian restaurant. Because of the awe in which they hold it, I expected it to be fancier, but it is casual in both decor and presentation. In retrospect, I shouldn't have been surprised by this. In my experience, south Indian food is designed to work with casual social situations.
The restaurant is in a nondescript strip mall across from North Dekalb Mall, which is itself a fairly nondescript mall. Atlanta has many excellent restaurants in strip malls, but Saravanaa Bhavan is the best restaurant in the seediest mall that I've seen so far. I've tried several dishes thanks to combinations, all of which were excellent. The bread that I had on my last visit (aargh, I can't remember its name) really hit the spot. On my first visit, I sampled the roti among other dishes, which I remember as being filled with a cool minty filling.