Gideon the Ninth is popular, but didn't work for me – the first third (or so) felt very muddled and I was wondering why everybody seemed to love this book so much. It got better, but the world it played in never felt quite solid to me, and I'd have liked it much more with just a bit less flippancy? Grimdark with aggressively flippant protagonist has been done to death. Quality of writing and worldbuilding increased throughout the book, apart from the final battle, and I enjoyed how the characters were fleshed out (for most of them, at least).