Basically it is an epidemic (a superflu) that wipes out the entire population except a select few. They all begin having dreams about two people: An old woman who is good and kind, and a dark man that is evil. They migrate to whichever side they are lured to and it is thought that they'd have to battle each other.
The beginning is slow. The middle is quite interesting and you want to know how it unfolds... the end is just terrible.
Read it if you want to, but those 1000+ pages lead to disappointment. =p
Stephen King... right now I'm not a big fan. I just finished reading the Stand... and I almost had to throw the book out the window in the ending. It was so terrible...