This is cross-posted from the Absolute Write message board.
When I choose a book to read, I'll look for things like genre, type of main character (shapeshifter, spy, pirate, etc.), whether it's an author/series I've read before, and point of view.
While I'm reading a book for the first time, I hope to be engaged by the characters, their situation, and the world they inhabit that I don't notice little details. Afterwards though, I like to page through the book and/or think about what I read, sometimes even reread passages to get a feel for how the author handled things like chapter length, opening hook, major turning points, character backstory and description, whether each chapter ends with a hook or not, etc.. These are also the same things that can pull me out of a story while I'm reading it.
Some other things that can pull me out of a story are unbelievable character actions/reactions to a situation, especially when it contradicts with the character's backstory, too much and too closely repeating one or two details about the main character while not including other details about him/her, really short or really long chapters, especially when the really long chapters don't have any scene breaks, and when every chapter has to end with a hook.
Some of these things will make me not enjoy a book as much as I could have, while others will annoy me so much that it'll just take me a really long time to finish reading the book.
As a writer, I just try to incorporate the things I like into my fiction while avoiding the things I don't like. When I get stuck, or what to know how an author pulled off one of these techniques well, I try to analyze their work to see how they did it so I can try the same in my own writing. I think that's why it's important for authors to read non-fiction books about writing techniques and fiction books to see practical applications of that technique.