I don't think it's possible to rave enough about this place. It's in the most random location on Old William Penn Highway, and if "location, location, location" is the key to a business succeeding, Udipi should be in trouble. The reason it's not is that the food is uh-may-zing.
I am giving this place full stars despite the fact that the layout and decor are awful, and feel like a cafeteria, and the staff is almost without exception unfriendly and refuses to make eye contact. You pretty much have to trip a waiter to get your drink refilled.
I don't even care, though. The food is heaven. It's nirvana on a plate. It's spicy and authentic and delicious, and I overeat every time I go there. They have a really large menu with a wide variety (something often missing in vegetarian restaurants), and I always have a crisis of indecision when I go there, because I know that it's pretty much impossible to go wrong.
Thumbs way, way up. Make the drive! It's worth it!