I don't think anyone can really argue that the Michelin Guide isn't a set of great restaurants, and that the restaurants earning 3* are pretty phenomental.
Sure, it's not an objective rating of the world's best restaurants, but that would be impossible to do. There are also bound to be great restaurants missed out as well as some restaurants which just don't deliver on visits.
Many of the best meals I've had have been at 3* places (Joel Robuchon Ebisu in Tokyo, Martin Berasetegui in San Sebastian, the Fat Duck in Bray), and am really looking forward to Joel Robuchon's 3* restaurant in Vegas on Friday provided I don't have any delays on my flights there!