I visited this place at least 3 years ago. It was a weekend and we drove there from Kitchener for lunch. Even back then this place was totally full. We had to wait a few minutes to be seated.
For starters we tried medu vadas and idlis and they were excellent! One of my friend's ordered their "extremely spicy" Kaara Masala Dosa. I ordered the Onion Rava Masala Dosa. The food was pretty good. The service was a bit lacking though. Well, after all it was a weekend and the place was packed as hell. The chutneys at this place were amazing. The sambhar was so-so.
This place definitely has some authentic food. My friend (with the spicy dosa) was like "Oh this is not so spicy" but you could tell that he was sweating and having trouble eating it. I tried a bite and it was definitely out of my spice tolerance range! Be sure to make reservations if you are visiting.