For those of us that have read all seven of the original Dark Tower novels, jumping back into Mid-World feels like coming home and slipping on an old comfortable flannel shirt. SK has created a special world here, a slippery mixture of fantasy, horror, scifi, and meta-fiction. Having said that, I'd be lying if I didn't think that the framing added anything to the story. Other than placing the story in the Dark Tower universe, the old Roland story didn't do anything to me - it didn't tell me anything new about the characters or shed any light upon the stories that followed--it merely felt like a repeat of the second half of Wizard and Glass. The other two stories can stand-alone by themselves, although readers not familiar with SK's world may find themselves somewhat confused by the way the characters speak as well as the particulars of the "fallen world" of the Dark Tower. Regardless, those who sit back and let a master storyteller drive for a while won't be disappointed.
I enjoyed this book immensely, ripping though it all 307 pages in five days. I've greatly enjoyed his "mature" writing style ever since Bag of Bones (the bloated Under the Dome aside), and this book's no exception. Check out this writing:
"At some point he slipped down their covering enough to see a trillion stars sprawled across the dome of the sky, more than he had ever seen in his life. It was as if the storm had blown tiny holes in the world above the world, and turned it into a sieve. ... He felt awe as he looked up at those stars, but also a deep and abiding commitment, such as he had felt as a child, awakening in the night, safe and warm beneath his quilt, drowsing half in and half out of sleep, listening to the wind sing its lonely song of other places and other lives."