Update, 6/23/17: 
 Halfway through listening to this this last time, I was tempted to back this down to three stars instead of four, but I think that's because I was annoyed with Stephen King as the audiobook narrator. It's not bad, but he's a better writer than reader, and he's hard to listen to after hearing his other stuff presented by such excellent voice actors. Frank Muller who reads the books preceding this is a really tough act to follow, after all. Plus, some parts early on are a tad dweeby, but it makes up for it later. So, at four stars it stays, or perhaps 3.5. 
 Original Review, 5/23/12: 
 We once again head to Mid-World, and learn more about Roland Deschain in what Sai King calls Dark Tower 4.5. I was excited to embark upon this journey, and was certainly not disappointed with any part of the trip. This book nicely explains how Roland's Ka-Tet got from the Emerald City to Calla Bryn Sturgis. It also wraps up some other stuff in Roland's past concerning how he deals with his mother's death. 
 I've always felt that something changes between books four and five. The first four have a different feel from the last three. I suspect most of it is due to the fact that Stephen King waited six years between the two, and during that time he got run over by a van which seemed to affect his writing style. I don't know if the accident was causation, but I definitely notice a correlation. This DT 4.5 book provides a more than adequate bridge, though. 
 I like the way the story is laid out. We start with the Ka-Tet which would be killed were it not for Oy, my favorite Billy Bumbler. It's nothing exciting, but Oy is responsible for saving their bacon though they have to lay low in some shelter for a couple of days. While they're resting, Roland tells everyone else a story that occurs just after the story he told in Wizard and Glass. While he's telling that one, he then tells a child the story of "The Wind through the Keyhole." Then he finishes up the story from his youth, and then the narrator finishes the story of the Ka-Tet. It's kind of like that movie Inception; we go three stories deep, then reemerge one story at a time, so everything is nicely nested. 
 The top story is just daily stuff; nothing too exciting. The second story is classic SK physical horror with plenty of gore. The third story involves a lot of King's cerebral Tom-fuckery. The third story is great because we get to see Randall Flagg, and I love it when that bumbling wizard shows up. We also learn some more about the guardians of the beam, Maerlyn himself, and what else North Central Positronics has been up to, not to mention some references to things that will be occurring in Wolves of the Calla. It's just a great segue. 
 You could read this story stand-alone, but I wouldn't recommend it. It's not because it would be too hard to follow, but because I believe you'll miss the full flavor of the Dark Tower series. There are just too many subtle references to things that would be easily missed. For those who haven't read The Dark Tower series, I don't think there would be any problem with reading this between books four and five even though it was written after the seventh book.