I am currently working through the copy edits on my second novel. Copy-editing (or should that be 'copy editing'?) is the most mysterious and most mundane part of the book-wrangling process, and the last piece of the puzzle before the text is sent off to be typeset. It's where the copy editor makes you look good, by picking up on and correcting typos, childish misspellings, clumsy grammar and/or general infelicities, and ensuring the whole internal cohesion of the book, so that Mondays aren't followed by Wednesdays, or characters with brown hair don't suddenly have black hair a hundred pages later. Those are the mundane parts (and like most mundane things, essential).
The mysterious part comes from the sense of another creative intelligence looking over your text and, very subtly, saying something like: Hmm... Well I wouldn't have done it quite like that...
A good copy editor is worth their weight in gold, and after my experience on The Unrecovered I'm pretty sure I've got a very good one. She's saved me from all sorts of minor mistakes, but there's still that wry sense of challenge whenever a word has been quietly replaced with something a little smoother. Sometimes the suggestion is a very good one, sometimes I'd prefer my original choice, and sometimes I really do want a comma there. I like this though. It forces you to look at things anew, and weigh up your choices once you've got a bit of distance from them. Going through the copy edits can be tedious in the extreme but, like everything in the publishing business, it really is in service of the quality of the book. It's the stage after this - going through the proofs - that's the real killer...