The Starting Out series by Everyman Chess is an obvious starting point for any flirt with a new opening. The series also contains titles on other topics than specific openings. One such example is Starting Out: Open Games by Glen Flear.
I have been brooding on this review for some time basically to figure out what I think about the book. The good thing with the book is the way GM Flear in a inspiring way presents the fine material. The downside is that it is unclear who will really benefit from reading the book.
"FCO: Fundamental Chess Openings" by Paul Van Der Sterren is in my opinion and excellent choice for a first introduction to opening theory. The book contains a few pieces of advice on almost all reasonable openings and the presentation is very readable. GM Flear's book "Starting Out: Open Games" is just as well written but more focused as it only deals with non-Ruy Lopez (non-spanish) double king pawn openings. A more narrow focus allows for a slightly deeper coverage of the openings discussed which of course can be a good think.
If I were to buy a single chess book (scary thought!) and the final choice was between "FCO: Fundamental Chess Openings" and "Starting Out: Open Games", then I would pick "FCO" for the wider coverage. However, for someone who whole heartily thinks that e5 is the proper way to defend to 1. e4, choosing GM Flear's book might be better. GM Flear is himself a devoted "e4 e5 player" and I think anyone planning to follow in his path will benefit from reading the book.
Ergo: The book is well written in all its parts but the parts doesn't somehow add up to an excellent book. As black, the book will help you improving your non-spanish double king's pawn defense. As white, I think it is a better strategy just to play through a lot of mastergames and then to find a slightly more specialized book on the openings you like to play.