The Crazies.
It was okay as disposable veg-out entertainment goes, but nothing more.
It sufffers the same irritations that ruin most of these type of films for me though, ie the ridiculous things the characters do to allow opportunities for drama and action. If the world has gone mad and the zombocalypse is upon you, stop splitting up and wandering off individually, FFS! And stay away from those dark, isolated corners with lots of "jumpy out at you" nooks and crannies!