A long time ago I had to read bits of this book in the original Greek, and it was tough going. So I am grateful for an excellent translation.
The book itself is a bit of an "They stayed here for three days..." 'Xenophon's intention now was to...' "Next Agasias stepped forward and spoke as follows..." sequence, all step by step, and some of the steps rather tedious. Especially when the various commanders endlessly discuss things, and this is faithfully reported down to the last subclause. But what a story it is! The 401 BC expedition of Cyrus against his older brother led to 10,000 Greek mercenaries marooned in what is now lower Iraq; they slowly walked and fought their way through unfamiliar territory with many pitfalls through much of Iraq and eastern Turkey to Trabzond ('Thalassa! Thalassa!') and then west to Greece.
Because of the democratic nature of the mercenaries (at least amongst themselves) they chose their own leaders; but in periods of least danger, there usually erupted bickering among those leaders, or they had to be newly elected. Xenophon was one of them, and bickered with the best of them; but also writes about the daily life of the ordinary soldier. Full of dramatic ups and downs, with plenty of boring bits but many more exciting ones, this is still an amazing book. To call it a classic sounds pretty stupid, as it is twenty-four centuries old - but it is still worth reading, whether you are interested in history, war, geography or the interaction of ancient Greeks, so similar to ours today.