The London reviewer is right. Michelin's guides have acquired such authority over the years that you might say that while others offer just opinions, the Michelin is fact. Those coming to Michelin for the first time will have to learn the symbols and codes: unlike most restaurant guides, written as a series of "restaurant reviews", Michelin has almost no descriptive text at all (the little there is was a novelty introduced only 100 years after the first edition) so its rating is all the more lapidary. No qualms here about being judgmental! As a result, you may want to carry other hotel and restaurant guides with you when visiting France, but you will always, always rely on the Michelin to tell you the truth about levels of comfort and the quality of cooking. And only the Michelin offers such comprehensive coverage. If there's somewhere decent to eat in the remotest corner of Brittany or the Correze, Michelin will know. Conversely, if a town has neither hotel nor restaurant in the guide, you just don't go there, it's a simple as that. By the way, when driving around France, use Michelin road maps. Any city, town or village with a place in the guide is underlined in red, so wherever you are, when you start to feel hungry, you know where to go!
One reservation as regards the London review: Michelin is not as reliable on restaurants in other countries, where you should always compare with a local guide; but you can still use it to double-check hotel standards before booking.
By the way, all the ratings are on Michelin's web site - but you'll still need the book of course when travelling around.