A really interesting-but-cautious high level history, zooming through 200+ years. It made me realise how little we know about the first world empire, and just how much of what I thought I knew was actually coloured by Greek stereotypes and propaganda that has persisted down the ages.
One of the main reasons I read this in the first place is that everyone knows the story of the Persian invasion of Greece, and the heroic efforts of the Greeks at Thermopylae and Salamis, etc, but that's all told from the Greek persepctive, and I wanted the persian one. Unfortunately it turns out we don't have *any* Persian sources for that campaign, but Matt Waters does his best to present it in terms of Achaemenid royal ideology and in context of the broader empire, and, spoilers, it turns out that the epic world-changing events of Marathon and Salamis were not actually that big a deal to the vast Persian empire. From their perspective, these were just part of many little border conflicts around the empire's fringes that most Persians probably didn't know or care about.
In the end there was quite heavy emphasis on Persia's interactions with the Greek world, and secondarily Egypt and Babylonia - i.e. the western half of the empire. This is understandable given our source material, and the prevalance of archeological excavations, but it did mean that the eastern satrapies of Bactria, Aria and the Indus valley were barely mentioned again after their initial conquest by Cyrus and Darius I (and even then only cursorily). The latter - the Indus - I was especially interested to learn more about, so that was a bit disappointing.
All in all this has definitely given me a better perspective on the Persians, and a good basis to go forward with reading about more Middle East history. I think the most telling impact that this book had on me was that, when it finally came time for Alexander's epic conquest, I actually felt sorry for the Persians now, and sad that they had totally lost their hard-won empire.