If you are going to just the areas included in this book, then it's a fine choice. Otherwise you might do better with a North India or an all India guidebook because there's not that much more detail here.
When I first saw this book advertised, I assumed that it specialized in what's normally considered the Northeast--Assam, Meghalaya, Arunachal Pradesh, Nagaland, Manipur, Tripura, and Mizoram. But these areas only comprise 50 out of the 376 pages! Most of the text is given over to introduction, Orissa, West Bengal, and Sikkim. An interesting chapter called "Excursions" briefly covers nearby places such as Varanasi, Nepal, Bhutan, and Bangladesh.