I loved the book.
King is wonderful when writing about someone growing up and reaching the limitations of their lives. He did such a good job of it in "IT" that on my second reading I had to stop because it was so realistic it made me depressed.
You have the kid from the shining all grown up, with all these powers, most writers would have made a bonafide super hero out of him, but King introduces what I feel real life into the character.
Genetic predisposition to alcoholism, bad family upbringing and a power that allows you to see stuff that is beyond your age to handle, all things that King handle superbly in this book.
And that is just a small part of the story!

Now I do want to mention one thing, and it is just a theory of mine and it's way out there.
I believe that at least part of this book was influenced by the nineties sitcom "Friends"
There was an episode where Joey and Rachel trade their favorite books
Joey's was the shining, Rachel's was Little Women.
It come's out that Joey get's confused by the characters in Little Women and thinks that one of the protagonists, Jo, is a boy. When he finds out Jo is a girl, he considers that the person She is interested in is named, Laurie, which he mistakenly thinks of as a girl. Aren't old names wonderful.
This leads to a line in which Joey says a lesbian sex scene was the only thing The Shining was missing.

Now this book comes out, a sequel to The Shining, and within the first 100 pages the main antagonist has a lesbian fling....