I think this billboard is challenging the stereotype of what is supposed to be the correct type of beauty, and drawing attention to the fact that these are not, and should not be the only things that make a girl "beautiful" enough to be on a billboard.
"Brilliant, Anderson." "Really?" "Yes. Brilliant Impression of an idiot." < So basicically Watson misses Sherlock about as much as Anderson is an idiot. < Was this supposed to be about Sherlock in the first place? Haha. Sherlock is taking over.