As an Iranian (persian), I have to say this show is barely relevant to the culture of iran (Persia). Although the story is great, I think, there are lots of things in the anime which are not exactly Iranian. names are not persian, except Arslan, farangis, tahmine, qobad and some others. Guilan is placed at north of iran but in anime it is in the south:person_facepalming:♂. Lots of arts used in the anime are styles which appeared after Islam (means after 600 A.D., too much later than the time of story). Music in the anime is Arabic and not persian. And there are lots of other stuff that mismatches real Persia.
But after all I'm still waiting for third season.

It has some interesting concepts and in some ways it's great that it tries to take a complex view of themes such as slavery and religion and the part these play in war. However, in the end this seems to boil down to being a series of impactful and thematic moments that fit the themes, but the TV show doesn't do the work to fully justify those moments and weave them into the story. Many characters seem far too two-dimensional as a result.

A great example of this is Kharlan, [spoiler]who betrays Andragoras out of loyalty to the true heir Silver Mask. He burns Parsian villages and sell out his country to Lucitania, and risks his own title as a lord... For what benefit? Why is his loyalty to Silver Mask so important that he's willing to give up practically every other principle he has? In addition, why are his own soldiers so eager to follow him in this when he's kept his loyalties a secret from them too? These motivations are not explored in the TV series.[/spoiler]