Despite the inferior quality of the photo reproduction I've always thought that Rough Guide is better value than Lonely Planet. It is generally more informative, more erudite, and the style is arguably geared to a wider readership, while LP leans more towards backpackers and gap-year students. I also think LP is more prone to hyperbole while Rough Guide is normally unflinchingly honest about places. It's perceived negativity is for me a bonus as it is often better to travel with lower or at least realistic expectations. As it says in the opening gambit, many travellers head for India expecting to 'encounter a timeless ascetic wonderland and are surprised to find one of the most materialistic societies on the planet'. I think this is pretty spot-on. There is no point in going to India and not being prepared for the filth, pollution, traffic chaos and inequality otherwise you will quickly need to reevaluate your trip on arrival.
A couple of criticisms: Rough Guide hotel information can be a little out of date by the time of your visit. Research on updating hotel email addresses and websites should be more thorough, although the publishing schedules for books of this sort make it almost impossible to keep up with the rate of change in a country like India. Also, I think that Rough Guide would benefit more from a Le Routard-style rating system for monuments and cities. Although travelling is highly subjective, more editorial guidance would be helpful for the traveller to distinguish between cities like, for instance, Jodphur and Jaipur. Empirically, there is a massive difference, Jodphur is a much calmer, better-maintained, less-polluted and more hassle-free destination, but you can't really predict this from the guide. Furthermore, this guide describes the lakes at Updaipur as "half-full" and a "trash-strewn puddle". At the time of writing the lakes had been fully replenished by monsoon rains and are certainly an essential stop on any Rajasthan itinerary. Nevertheless, this is still the best product of its kind on the market and a must for all visitors.