I was expecting The Manager, which I assumed was the dark shape leaving the hotel at the end of The Shining, to show up in DS. Missed opportunity for a good villain that would further have justified a Shining sequel.
The ending I didn't like because we followed Danny for two novels, yet it ends with him sitting in a room with a Fred, a character I don't care about, and seeing his uninteresting past. Then Fred dies and I'm like "yeah, okay, whatever". Then the book ends and I'm like "uhm".
While the prologue was good and Danny, Wendy and Dick were consistent and recognizable from The Shining, I didn't particulary care how it retroactively made The Shining less scary by saying that the whole time Danny could have just , in quite comical ways, locked the ghosts up in imaginary lockboxes without breaking a sweat.