I've been here twice and wasn't too impressed on either visit.
I really liked the ambiance inside the restaurant. There was a page of vegetarian entrees, many of which looked very appetizing. Unfortunately, our server was very young and not really able to answer our questions about vegan dishes. I ended up ordering dal makhani and roti, which she was "pretty sure" did not contain dairy. I was relatively confident that the dal was a safe bet (and it was delicious, though quite soupy), but the roti came brushed with some kind of glistening substance. I'm not sure if it was ghee or oil -- I'm hoping the server mentioned to the cooks that we had requested non-dairy preparation. It didn't seem like she had written it down.
Out of the four local Indian restaurants I've visited, New Delhi Palace's roti was definitely the best. It was thick and layered, with a slightly chewy texture. Vegans should probably specify that they want it brushed with oil (or nothing), just in case that is not the default preparation.
My companion had the Madras vegetables, and we both agreed that it was pretty bland. It was, however, very filling. On a later visit, I had the channa masala, which was pretty good but too tomato-heavy for my tastes.
The second time I came here, I had a similar experience. Another teenage waiter who was unable to answer questions about ingredients. For vegetarians this won't be a problem -- just order off the vegetarian menu. Vegans might prefer to go to Indian restaurants whose waiters actually know about Indian food.
I have a feeling that I would rate this place higher if the servers had been more knowledgeable about the food. As it was, the servers we had made me a little nervous with their lack of knowledge about the dishes' ingredients.