I enjoyed reading them aloud when my oldest was little, but when I started them with my youngest a few months ago I really didn't enjoy them anymore. Some are definitely better than others.
A really good author to take a look at is Chuck Black.
http://www.perfect-praise.com/ I have only read one book in the Kingdom series (the last book), but it is a "lighter" read than the Knights of Arrethtrae series. Girls will definitely enjoy the latter series because there are leading female characters. Each book (in both series) also has discussion questions for each chapter. They were a fave with my oldest.