I visited Sarvana Bhavan twice last month. The portions are small, except maybe those of rice. The main course dishes invariably disappointed me. Onion uttappam was about 5 inches in diameter and I had to search for "uttappam" within the sliced shallots. The chutneys and sambar were great, nevertheless. Rasam was ok but served in a beer mug. They expect their customers to drink it like juice/ beer?
The service is very, very rude and not prompt at all. Going there isn't worth the expense.