I have just returned from a one month holiday in Bangladesh and Northeastern India. I was hoping for a more region-specific guide but there isn't one, so I had to carry this bulky country-wide guide with me.
This appears to be an excellent guide for the more "usual" destinations in India, but people should be aware that it barely covers Northeastern India at all. Part of this is due to an editorial decision to drop information from prior editions due to political instability in many of those states, but the decisions on which areas to drop do not match local knowledge about which areas actually might prove unsafe for foreigners as opposed to local politicians. Granted, it is an ever-changing scenario, and this guide is by now a few years old.
My main complaint though is the maps of the hill stations; particularly those of Darjeeling and Gangtok. They are just plain wrong, and not to scale (even in cases where they say they are to scale). Unfortunately the Indian government tourist maps for those towns and also Kalimpong are also wrong, and not to scale either, but are somewhat more helpful, so my suggestion is to visit the local tourist offices immediately upon arrival in each town and pick up their official maps.
In both cases, however, contours are missing, and considering that these towns have several hundred to several thousand feet differential between top and bottom, and that there are no pedestrian steps to cut across the time-consuming road switchbacks, one can easily make a wrong decision at a switchback crossing and miss a major point of interest (such as the major monastery at the top of Gangtok). At the very least, since most roads are one-way (and few if any are marked), showing directionals would help.
Considering this edition is many generations removed from the first edition, it is not acceptable that directions are often completely inaccurate. For instance, the major monastery outside Gangtok is listed as being to its east, when it is really to its southwest (but I did find it). And in Kalimpong, I missed the main monastery as I ran out of time after going more than twice as far as the stated distance and still not reaching the monastery south of town (which R.G. listed as being at the top of the hill, when ALL of the locals that I asked confirm it is near the bottom!).
To be fair, the Lonely Planet guide is much, much worse all around. I have just ordered the Footprint guide to see if it is more accurate and complete for this region of India. I would at least like an accurate reference for matching against my trip notes, photos, and writeups!
As far as the non-Himalayan eastern states are concerned, there is almost no coverage at all, for the previously stated reasons, but hopefully this will change in the next edition, as travel restrictions are blightening up and it is now possible to arrange permits for Aranchal Pradesh and Naga just a few days in advance (quite easy if you sign up for a local multi-day tour based out of a major town such as Guwahati in Assam).
It would have been helpful to be more specific about which languages are spoken in which towns/regions, as this area is quite a patchwork, and also to mention the likelihood (or not) of encountering English speakers. As it turns out, the main hub for northeastern connections, Siliguri (in the northern part of West Bengal state), inexplicably has almost no English fluency at all, even though ALL travelers must pass through this town to make onward connections. Most resourceful travelers can work through this though, but travel guides need to also guide the more timid tourists.
I will give Rough Guide credit for fairly good descriptions of the major highlights and how to reach them (which is quite difficult and more than one can ask from a guide that is only updated every two to three years). As always, they are the most culturally sensitive guide book and take the most effort to go for first source information (vs. Lonely Planet's habit of quoting second source information that is incorrect, without bothering to check it out -- and I am referring not just to location based information, but also cultural and historical background).