This book has been in print since 1985 - proof enough that it's not just another vegetarian book or indian cookbook, but a particularly good one. The recipes are excellent - some of them intriguing; the introduction is thorough; the index is good; recipes sometimes include ingredients that can't be found outside India, for authenticity's sake, but alternatives are also suggested in most cases; and the writing style is clear.
But I won't give it 5 stars. To me, a book is the responsibility not only of the author, but also the publisher. It's just not acceptable to leave errors in a 20-year-old book, such as the dish from Mysore that turns out to be from Bangalore, or a reference to Tanjore as the site of the Meenakshi temple (that left me wondering - did they get the temple wrong, or is the recipe from Madurai?). Also, if I'm going to pay for a hardcover edition, I expect it to be durable, not start falling apart at the (glued-together) seams the minute I start using it.
Also, I agree with another reviewer that this book should have had a lot more on other grains, especially millet and sorghum which are very popular in India but almost never available in restaurants.
And I might as well mention my pet peeve with both Sahni's books: why the distinction between side dishes and main dishes? I find it meaningless - it would have made more sense to put veg with veg, dal with dal, etc.
Still, if you like Indian cooking and don't want to limit yourself to what your corner curry house can offer, and if you want to learn about a vegetarian tradition which is far and away the richest in the world, you will find this book very enjoyable.