I just sent the final post-copy-edited chapter of the book back to my copy editor.
My copy editor is great, and the book is a hundred times better because of her, but I'm so glad that I'm done with this part of the process.
Getting a copy of a chapter back with a thousand little notes on it about things you need to fix is just so disheartening.
I recently saw a description of the process of writing a technical book as being similar to "Having your teeth pulled out with pliers, slowly, over the course of a year". It's been a bit more than a year for me, but other than that it's about right...