A legend is, I think, an obvious requirement for color coding anything, generally speaking. What's cool about this is the degree to which the diagrams are standardized and how functional they are in the mobile context. I think the idea of *not* including the information about one seat being more desirable than the next is interesting given the significant value that information theoretically holds (and the fact that such debate can often be addressed via seatguru) but I get the appeal of avoiding that kind of subjective debate. That said, it seems like there could be some middle-ground here, where there isn't discussion of the merits of a given seat, but still useful annotations specific to said seat (seatguru tries to do both and achieves varying levels of success in my opinion.)