Personally I give credit to the series' appeal partly to the gritty and realistic art style the comic adopted early on in the series. Readers of the comic know that after issue #7 the artist changed from Tony Moore to Charlie Adlard which completely changed the art the comic originally debuted with.
Initially the art style consisted of characters and environments with more of a cartoon or manga vibe. Things generally seemed happier cause art was heavy on the solid outlines and more on whites creating the allusion that you were really looking at a drawing. The comic then changed to an art style that was heavier on the darks and shadows. The word "gritty" really encapsulates the feel and tone. Characters started looking less like cartoons and more like real people.
This obviously went hand in hand with the theme of comic, that being more about the reality of the situation and less about ZOMGZOMBIES. It really makes me wonder though how successful the series would have been if not for the change of art. Do you think maybe the art was secondary and it was mainly the writing? Maybe the art was a turn off and you liked the original better. Thoughts?