Once you get past the first half about the plague, it becomes a pretty small story. SPOILERS
Usually, epics start small and grow bigger and BIGGER until you reach a huge climax. In The Stand, King starts with the end of civilization, and then it all just fizzles out once the good guys reach Boulder... We end up with basically two small towns in a Cold War, lots of small-town politics and a handful of guys sacrificing themselves in a contrived Deus ex Machina ending.
King was trying to write a modern American Lord of the Rings, but it's very unbalanced. Nothing about the conflict between Boulder and Las Vegas lives up to the opening half. After the huge drama of the plague, the ending was a big let-down. You close the book and think "Jeez, is that it?"