Under the Dome: A Novel - Stephen King

I expected this book to be so unbelievably good, as it was written by Stephen King and some of my friends always tell me everything he has written (and they've read) is pure gold. And, besides that, it's Dystopian. So, how bad could it be?

The story seems a bit similar to the Gone-series (Michael Grant), with it's first book published almost simultaneously with Under The Dome (at least in The Netherlands). 
An enormous sphere is placed around a little town, trapping everything -and everyone- who's in that town at that moment 'under this dome'. As is often seen in Dystopian novels, control and 'normal human behavior' is one of the first things the people run out of. Survival of the strongest (not necessarily the fittest, but just the persons handling the guns). 

Problem just was that I thought it to be boring sometimes, there were so many characters, and normally I don't mind, but here it really was a lot. And there was quite a high body count as well (and fast, normally I wouldn't expect a total loss of control just that fast).
What I didn't really liked either was how King was giving away everything with a bit of suspense that was about to happen. *SPOILERS FOLLOWING* For example, a man decides to go and shoot people in a police office. Okay, you think. But before he does shoot this people down, you get to read 'I'm going to go to the police station now to kill some people'.
Surprise, surprise, what would happen next? 

I really wanted to like this book, but because of these things I just thought it to be a very long read, with it's almost 900 pages.