Wow. So I just finished reading a 500 page novel in one day. It's been years since I've done that.
"Doctor Sleep" is worth a read. It starts off like gangbusters. The first half of the novel is especially amazing. In the second half, King slips into some of his more maddening habits. (There's a hundred page section before the big climax that has a lot of filler in it. He also plants secrets for big reveals later that fizzle mostly from making too big a deal of themselves.
In the final analysis, it's a worthwhile yarn even if it is a less than worthy sequel to "The Shining." No matter what, the inevitable movie should be pretty good.