Er...depends on your definition of "works good" !!
Just tried 2010. The paper size problem doesn't seem to be there, but the pagination is just as bad. Lines of text are different lengths in the edit screen and the print preview screen - the margins seem to be narrower in the print preview.
Checked 2011 again - Initially I thought the text doesn't seem to move between lines, but I now notice it is happening here as well. There is also something very strange about the way the widow/orphan processing is happening. You get to the end of a page and it starts a new page. Then after the first line on that new page if you keep typing the first line suddenly leaps back to the previous page. Sort of the opposite of how the widow/orphan handling should work!
There is a good reason why Word has taken 30 years to develop - creating a word processor isn't a trivial task. I think Ancestry have bitten off more than they can chew here.
Images are a pain in books as well - you can drag and drop them in nicely, but there don't seem to be captions, and you can't get the text to flow round them. In future I think I'll stick to Word - although I might create all the diagrams I want as a book and then export to Word, rather than trying to export them individually.