The Crown Tower: The Riyria Chronicles, Book 1 starts with a nice forward from the author, Michael J. Sullivan, where he explains why he decided to write the prequel stories, The Riyria Chronicles, after having published The Riyria Revelations. And in the forward he says that he wrote them in a way that readers could enjoy reading the stories in order of publication (Revelations first, then Chronicles) or in order of events (Chronicles first, then Revelations). Having read all The Riyria Revelations books and now having listened to the first of The Chronicles, I think that is mostly true - you could follow the story in either order. However, The Crown Tower is bound to be a joy and great fun to anyone who enjoyed The Revelations, but isn't likely to be as compelling to those who have not. All the world building and plot setup is done in The Revelations and you just aren't going to understand what it means when someone says, "By Maribor,....", the hostility toward "the church", and some other references in The Crown Tower without reading The Revelations books. The Revelations is the place to fall in love with Michael Sullivan's world and its characters; The Chronicles provide icing on a really great cake.
If you have already read and loved The Revelations, you are gonna be thrilled with The Crown Tower. The boys (Hadrian and Royce) are back, but not quite the amazing pair they came to be in The Revelations. The Crown Tower goes through their first adventure together forced on them by Professor Arcadius (remember him??) and we get some wonderful insights into how these opposites came together to make such a great team. Michael Sullivan's style is consistent - quick paced, great settings, good plotting, even minor characters have dimension, and very witty dialog. One other similarity with The Revelations; Sullivan writes great fight scenes even for a reader like me who isn't too into the normal violence of high fantasy. In addition to taking us back to the beginning of the daring duo, The Crown Tower gives us an origin narrative for Gwen which I found surprisingly compelling. I will admit that I wasn't overly fond of the Gwen character in The Revelations books - mostly only liked her for her protectiveness of Royce. However, when you get the back-story on Gwen, she becomes a much more sympathetic and understandable character.
I really like the pairing of Sullivan's writing with Tim Reynolds narration. Not only did Reynolds do the narration for The Revelations books which keeps The Crown Tower sounding nicely consistent, but Reynolds seems a natural for Sullivan's books. Reynolds shades his voice more than changing it for character voices/accents, but it is plenty to make the dialog easy to follow and keeps Sullivan's very adventuresome writing from sounding "over the top" while still maintaining a nice narrative tension throughout the book.
If you haven't read The Riyria Revelations books, please start there and if you like high fantasy at all you will love them. If you have read The Riyria Revelations, dive into The Crown Tower and be prepared to not want to stop until the end of the book. This is a totally satisfying listen that will still leave you wanting MUCH more!!