You guys might be missing the point - the game is trying to put a MASSIVE emphasis on style... something that is rarely done in the video game world. Its based on an actual comic book about conspiracies and whatnot - so the storyline will probably be somewhat intelligent and enjoyable (unlike 90% of FPSs).
The cell shading is done to keep the game looking EXACTLY like the comic... not as a gimmick.
"When the bomb drops it'll be a bank holiday
Everybody happy in their tents and caravans
Everybody happy in their ignorance and apathy
No one realizes until the television breaks down..."