Complex sentence: It is not intended to be a guide of good manners, but rather tries to give a descriptive approach, although as the author often also reveals his opinions on certain problems of behaviour, the book does give some orientation.
Split into simpler sentences: It is not meant to be a guide of good manners, but tries to give a rather descriptive approach. But as the author often also reveals his opinions on certain problems of behaviour, the book does give some orientation.