I think Wybrew is incorrect on a few things, but the book is definitely worth looking at. Just make sure that you try to read it with an open mind but also a critical one: Wybrew is not the final authority on all things liturgical or Orthodox. (He is Anglican, and I don't believe that liturgy is his discipline of expertise.) Still, it is a very thorough treatment considering its small size, and I think that he is right on target about many things in Eastern liturgical development.
Fr. Robert Taft (a jesuit of the Byzantine rite!) is widely renowned as a scholar who has looked at Eastern liturgical development from an historical perspective. You might want to look at his The Byantine Rite: A Short History.
I highly recommend Fr. Alexander Schmemann's For the Life of the World and Liturgy and Tradtion (edited by Thomas Fisch) for a greater understanding of the meaning and purpose of liturgy. (I know that there is a great dislike for Fr. Alexander's works in some circles, but don't let that stop you. There is also a great deal of enthusiasm for his work as well.)