This is in the modern fashion of part-documentary "enhanced" by reconstructions. Unfortunately the result is an annoying mish-mash that fails on every aspect of telling the story.
As has been commented the historical experts comments are (in the most part at least) clunky and it feels like they are reading a script that they have never seen before. These experts also make more than one very dubious statement - "a million men in the Persian Army" REALLY ???
The reconstructions have appalling costuming and armour and I would comment that the acting was poor except for the fact that I didn't actually see any acting ! As with the experts, the reconstructions were no more that people saying (or more often shouting) a line with no sense of meaning in their words. And I really want to make no comments at all on either the Greeks' armour or their fighting style, neither certainly bore any resemblance to anything seen in Ancient Greece...
This MIGHT have been better without the poor reconstructions, although even then the experts would have struggled to keep an interest which even they didn't seem to have in the subject.
There IS a good story to be told here but there are considerably better documentaries available on the subject, but this one is not a success on any level.
A great disappointment