What I found was rather different to what I expected. This is not an academic history as we know such things, but a commentary on contemporary international relations, propagandistically crafted for a particular domestic interpretation in Athens, rather like most of the books you can find in shops on the War on Terror or the Cold War. Thucydides' use of rhetoric, his visibly partial citation of evidence and his dramatic reconstruction of conversations at which he was not present are all familiar tactics from today's literature. He would have been very much in his intellectual element as a crafter of drama-documentaries. I rate it as fascinating artistically - particularly the complex character of Alcibiades - but barely history.
I blame Thucydides directly for the useless mess that is most academic research into international relations. In Thucydides' account (the Melian dialogue is the most obviously fictional passage, but there are many others) decisions about war and peace (and, later in the text, internal revolution) are made on the basis of perfect or near-perfect knowledge of the international and local situation, after mature reflection and rational debate of the alternatives. It's a lovely fairy-tale and it's not surprising that many people choose to believe it; I had not appreciated, however, that it went back so far. Irrational decisions are only made by the deranged, who are normally anonymous (eg the people of Corcyra in 3.84, or the Syracusans who mistreat the Athenian captives in 7.86-87).
I know I'm not being fair; Thucydides is at the very beginning of recorded history, and it is amazing that a book written 2430 years ago is still lucidly intelligible (and interrogable) on its own terms. Pericles' funeral oration (2.34-46), in particular, whether by Pericles or Thucydides, is a brilliantly eloquent appeal to the emotions of those who have lost their loved ones in the service of their country, and is far ahead of anything else I have read on that subject in terms of literary quality. But I think his inability, for whatever reason, to examine the cultural context of his time, and to be honest about his own political situation, weakens the truth of the book.
Apart from the general issue of the book's ideological purpose, there are a lot of interesting points of detail here. As a lapsed astronomer, my eye was caught by the three eclipses mentioned, especially the first, where we are told that "the sun took on the appearance of a crescent and some of the stars became visible before it returned to its normal shape" (1.28). I was a bit surprised about the stars becoming visible even though this was not a total eclipse. A little research, however, got me to Mercury being close to maximum elongation 25 degrees from the Sun, and Venus approaching superior conjunction and 15 degrees from the sun, and I suppose both would have been visible if the Sun was sufficiently dimmed.
In 5.16 we read of accusations that "Pleistoanax... and his brother Aristocles had bribed the priestess at Delphi to give oracles to the Spartan delegations, commanding them to bring home from abroad the seed of the demigod son of Zeus". The what??? of who??? I checked the original: Διὸς υἱοῦ ἡμιθέου τὸ σπέρμα - what on earth can it be? Edited to add: Thanks to chickenfeet2003 and paratti for providing me with the answer in comments. I was imagining stolen vials filled with supposedly semi-divine semen, but of course Pleistoanax actually just meant himself and his brother.
Snerk in 4.84 about Brasidas, who "was not at all a bad speaker, for a Spartan."
Anyway, very glad to have finally ploughed through this.