The Shining is one of my Top 5 all time favorite books, and has been for 20 years, and so it was a scary thought that Doctor Sleep could potentially change how I feel about it. Thankfully, that wasn't the case, but I will say that my opinion of Jack is a little... altered.
The Shining is all about Jack Torrance for me; The Overlook, and even Danny, are secondary. Jack's character is so realistic that he could step off the page, swinging his roque mallet, and bellowing "Come here, pup!"... and that's what makes him fascinating and terrifying to me to this day. But I love him, and I have pretty definite opinions of his character: Jack was a fundamentally good but flawed person with asshole tendencies, who was dealt a shitty hand in life, and got in over his head in a situation that he couldn't understand and was massively unprepared for. He was always going to lose against the Overlook, but had he avoided that place, I'm certain that he'd have broken the cycle of alcoholism and violence. Now, after reading Doctor Sleep, I don't think I can say that my faith in him is shaken, but just that there's a crack along the line that separates "fundamentally good" from "asshole". How much of that crack can be blamed on the alcohol is debatable. Probably a lot... but I think that would be a cop-out and honestly I think Jack knows better than that.
So, coming back to Doctor Sleep, I've always felt that Stephen King looked at Danny as his fictional son. I commented on this to my friend on the drive up to Boston, because I was surprised at where King imagined Danny to end up. Of course it made sense, but I wonder if it hurt King to write him there... drunk, and hitting his rock bottom, and wanting desperately to find a good place to escape his own personal demons. I hope it did, because, even though Danny doesn't hold the same place in my heart as Jack, seeing him come back into the world as a violent drunk who hates who he's become was a little painful for me, considering his familial history. I so wanted him to avoid that.
Unfortunately, I can't say Doctor Sleep came anywhere close to being as great as The Shining, but it was very good for what it was. There were times when I felt that things were rushed along a little bit, and timees that things were a bit too easy, and times when the build-up overshadowed the reveal, especially in regards to the final showdown, but for being a continuation of Danny's story, it was good.
I liked the person he grew into being, and I liked that he used his ability to help those at the end of their lives. I couldn't imagine doing something like that though, seeing the lives of so many people, so intimately, and caring enough to stick it through with them to the end, when even their own family couldn't, or wouldn't. That would be too much for me, but it makes me oddly proud that Danny was able to do it.
As far as Abra... I dunno. I'm more ambivalent about her. I feel like I was supposed to love her, but I just... didn't. Things were just so easy for her, since she was so powerful in the shining, and on top of that, she had a support system - two parents, Danny, Billy, and John. And she was more than twice Danny's age when he had to fight for his life, alone. So I just didn't really feel all that concerned about her, as unfair as it may be. I feel like King went easy on her.
I also wanted to know more about the True Knot. I wanted to truly fear them, but aside from their ruthlessness and their obvious financial means helping them to get away with it, I didn't find them particularly frightening. I wanted more along the lines of Horace Derwent and the dead woman from Room 217, and what I got was the Wicked Witch of the West. Hat and all.
In a way, Doctor Sleep was quite a bit like Black House, and I imagine that people will compare them. I don't think that as stories go they do compare to each other much once they get going, aside from the fact that they both revisit characters who experienced crazy events in their childhood after a long gap of time and catch up with their adult selves. I really enjoyed Black House, and feel the same about Doctor Sleep. And, as with both big-gap sequels, I like that they were doorways into King's larger universe, and now Joe Hill's as well. Some great little Easter Eggs to find there, and I loved that.
So, overall... I liked it quite a lot, but I don't think that it lives up to The Shining. It's a good continuation of Danny's story, and a good standalone novel as well (because it CAN be read that way, if you don't mind getting the really short and sweet version of a recap of The Shining), and I'd definitely recommend it to King fans.