My own thoughts on the Legacy of Persia DLC for CK3: I'm a little disappointed, I guess? I thought we were getting a large overhaul of regional struggle that would apply mechanics of interest to both start dates and would have a large effect on gameplay like we got with Iberia. We kind of didn't get that. The struggle mechanics don't last really that long and feel mostly reused from the Iberia stuff outside of the Turkic invasion CBs. The Turkic conquests feel really unfinished and the AI really likes to spam Turkic invasion wars ad nauseum. The Seljuks, the most important of these nomadic conquerors, just kind of appeared in my game and weren't really a challenge. There is a neat little mechanic where you can vassalize them, but it's kind of janky and you lose them to their conquest of Arabia if you don't already have the caliph defeated. The new taxation mechanics are really cool and add a lot of historically accurate flavor until you see that the Muslim and Zoroastrian taxation holding types are the same for some reason. There's new stuff with clan government and keeping your house unity up, but it's pitifully easy to make your family members like you. All in all, none of these mechanics really make it to the 1066 start date outside of clans and taxes and none of them feel fleshed out quite enough as the various endings of the Iberian struggle stuff. It's probably still worth it for more historical flavor though. You do get a lot more to do as Iranian culture characters and now Abassid games aren't a cake walk anymore. Lot of really pretty clothes and coat of arms updates too. 8/10 aesthetically and in terms of just pure content. 5/10 in terms of how polished the DLC is overhaul.

Note: This is after a restoring the Sassanids playthrough.