Having been to South India we were looking for good South Indian food. For the uninitiated it is very unlike the standard (northern) Indian food you find in most restaurants. South Indian tends to be entirely vegetarian and features dishes like dosa (thin crepes often filled with a spicy potato mixture) and idli (steamed rice and lentil cakes served with a spicy vegetable stew called sambar). No naan or heavy curries here.
Chennai Woodlands is about a 30 min. drive from Boston/Cambridge but was worth the trip. The place was packed on a Saturday afternoon with Indians -- we were the only non-Indian folks in the place -- and the menu features a full range of South Indian dishes. We had the buffet which featured about a dozen all-vegetarian dishes, including the aforementioned dosa, idli, and sambar. Be sure to order chai after your meal and do like the Indians do -- pour it between the cup and the saucer to cool it down before drinking.
The food was very authentic although it was not as good as that we had in South India. I found the sambar to be a little weak - not quite spicy or tart enough - and the coconut chutney was a bit bland. However ... I would still recommend this place as a good way to get your South Indian fix and try a bunch of authentic dishes all at once.