The very first book was mostly a backstory to the series.
The second book was the first "in the story" of the series.
This, the third, is mostly King going "Well, now I'm writer, I can write whatever I can". And so he does.
The story flows nicely and a lot of things that you could feel King was holding back in the second story are not here. Whatever he things he can do, he does. So the story goes into larger arcs, deeper content and so on.
The only downside is the ending. About 10% of book you feel like that "Oh shit, he's not going to defuse the bomb" or whatever happened in the old TV series and you can feel the "To be continued." coming.
And "To be continued" comes.