Per another comment;

Herodotus' account is pretty favorable toward the Persians in many respects. He sings high praises of Persian culture and art. He's not completely free of Greek biases, but he had a much more circumspect attitude on the Empire than the Athenians or the Spartans. Unsurprising since he grew up mostly under Persian rule (more Greeks lived in the Persian Empire than in what we call Greece).

Herodotus wrote narrative embellishments, but a lot of people overlook that he examined the stories he collected and cast judgements on them. Herodotus would often tell a story and then explain why he thought it was or wasn't true. People tend to only note he told the story and forget he was analyzing his sources more than they realize.

Propaganda and badmouthing the Persians wasn't quite his deal. If anything he wrote the most Persian favorable version of the history out of all the Greek writers who survived the Classical age.