These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Always Chaotic Evil: Herodotus usually abstains from judging other cultures, but occasionally describes peoples as this, such as the cannibals from beyond the black sea.
Broken Base: "I have now reached a point at which I am compelled to declare an opinion that will cause offense to many people, but which nevertheless appears to me to be true..." Herodotus was certain that he broke his base by stating that Athens was just as important, if not more important, than Sparta in fighting off the Persian invasion. As of his statements on many Other matters, such as the events leading to the Trojan War, may not have been base-breaking enough for macho bro Hellenes.
Fair for Its Day: Herodotus notes an old Babylonian custom of betrothal - the prettiest girls were auctioned off to rich men for a lot of cash. The money then went towards subsidizing ugly and crippled girls, so that humble men would get paid for marrying them. There was also a quick and efficient mechanism for divorce, in case a couple did not get along. This was considered by Herodotus to be better than the alternatives - prostitution, crippled girls being unmarried, etc.
Crowdsourced medical diagnosis, rather than relying solely on some specific profession of people - totally novel to Herodotus, but now we live in the age of Wikipeda, WebMD, etc.
Signature Scene: "The Hellenes who were waiting in this region [Thermopylae] were 300 Spartan hoplites, 1,000 men from Tegea and Mantineia, 120 from Orchimenos in Arcadia, and 1,000 from the rest of Arcadia. From Corinth there were 400 hoplites, from Phleious 200; and there were also 80 Mycenaeans... From Boeotia there were 700 Thespians and 400 Thebans. In addition to these, both the Opuntian Locrians, who had come full force, and 1,000 Phocoans had responded to the Greek call for assistance."
"If you attack the Persians then a great empire will be destroyed."
Values Dissonance: Quite apart from the numerous ways the ancient cultures' ideas of morality and proper conduct differ from our own, they often differ from one another. In fact, in many ways, Herodotus is an early proponent of the idea of judging cultures by their own traditions of right and wrong rather than one's own.
Vindicated by History: The Histories has always been considered a classic, but it was more for its literary merit than historical. Herodotus was called "Liar" in his own time and widely accused of making the whole thing up. Modern archaeologists and historians, however, have corraborated many of his stories. Today it's believed he was accurately retelling stories that the locals he spoke to believed to be actual history.
History Marches On: However, other claims have not really been borne out by later research, especially the numbers he cites. In particular, he or his sources seem to consistently exaggerate the number of Persians that invaded Greece; the best example of this is the battle of Plataea, which is described as a Greek force defeating a much larger Persian force through tactics, equipment and training. However, archaeological evidence suggests the two forces were fairly evenly matched, with some sources going so far to claim a slight numerical advantage in favor of the Greeks.