This is a standard and authoritative history of the period from 60BC to AD14. It was first published in 1939, and seems to have been available ever since. Every book on Augustan Rome, the Republic, or any related matter always refers to this book - this book just seems to be a definitive reference to any writer, whether they ultimately agree or disagree with the author's viewpoint. Funnily enough, I've just discovered he was born and raised in New Zealand! Fancy that ...
I read the first half of the book when doing a paper on Early Rome (up to the fall of the Republic), and have now read the rest of the book preparatory to doing a paper on Imperial Rome. So it seems a good time to review the book as a whole. Given that the book was first published in 1939, it seems almost inevitable that the author's views were coloured, to an extent, by the rise of fascism in Europe at the time, and the impending threat that hung over Europe. Syme attributes fairly "black and white" pragmatic attitudes to Augustus' methods and plans; and while that may not seem so shocking to us now, it was probably fairly reactive at the time.
This is most definitely not an easy read, and not to be attempted by a reader with no prior knowledge - the narrative moves from names to places rapidly, and assumes a familiarity with these which are vital to an understanding of the overall theme of the book. Syme approaches the period in a vaguely chronological order, with wide divergences into thematic topics. The writing style is very scholarly and very "old school", so it's a book to study, to think about and to study while referring to other sources as well, to bolster the opinion and knowledge gained.
Highly recommended for anyone seriously looking into the end of the Roman Republic and the birth of the Roman Empire.