From what I have seen/read about HK and beta feedback, my biggest worry is the lack of personality.
Civ has memorable leaders and factions, Endless Legend had very unique factions(leaders were bland though) but Humankind doesnt have that at all.
I really dont warm up to the changing cultures either, like how your enemy morphs between nations. I like how in Civ your empire has its power eras andnsome bonuses that are useful for each era.
It seems that HK ai doesnt play with the same rules as human player when it comes to combat and some mechanics, it is also annoying when it happens at civ like how in Civ 5 ai doeant pay upkeep for armies.
I feel HK has some "emperor's new clothes" going on for it with some people, but we will see, I am definately curious and might buy it if it impresses.
As I've posted elsewhere, Civ and HK are taking their basis from different schools of historiography: Civ the Great Man view of history, HK the Great Forces view (once upon a time called "Marxist"). I agree, that means that in HK there are no Great Men (or Women) - in fact, no named individuals at all, in any form. That will take some getting used to and will definitely not appeal to some people.
On the other hand, I think (from what I've seen) that HK models the long-term trends in history better, and gives the gamer some very interesting interactions/decision-points between Problems brought on by long-term interactions with other cultures and factions, available resources and trade opportunities, and diplomatic interactions and gives the gamer a better 'feel' for how individual decisions by the gamer can affect what happens to his faction in the game. We've yet to see, of course, how well all that will work in the game when it is Released and subjected to play by a vastly larger group than any 'test' group they've exposed it to.
And I was extremely sceptical of the 'changing culture' mode when I first heard about it: as an avowed historian, By Herodotus I want to see historical progressions: Greeks to Byzantines, Zhou to Han, Tang, Song Chinese, etc.
But, after playing with it through several OpenDev iterations, it grows on you. For one thing, each type of Faction has a different ability/attribute that carries over into the succeeding Eras, so that after 2 - 3 varying choices, your Medieval or Early Modern pick does not have quite the same attributes in every game. To some extent, then, you 'build' a unique Faction the longer you play, until your Modern Australians can have 'bits' of Khmer, Mycenean, Siamese, Ming, and Austrian in them - or any other of myriad combinations. Again, it will be interesting to see how gamers 'take' to this in the marketed version of the game.
Finally, based on comments from some of the VIP testors and other hints, it appears that the oher Major Factions do play under rules similar to the Human Player, unless you play at higher or lower than 'average' difficulties. Like most computer games (and all the Civ variations), the difficulty differences are based almost entirely on the amount of 'cheats' given to the human or AI players. On the other hand, (and this is Very different from Civ VI, at least) the AI and the human seem to be pretty evenly matched in Tactical Battles - the AI uses terrain very well, picks its attacks pretty well, and seems to know when to go on a 'hedgehog' defense to extract the maximum losses from the human's units when there is no other good tactic available. Again, it will be interesting to see how well it all works with thousands of players trying it in the (presumably) 'tweaked' release version of the game. - And at least in the Open Dec versions, the AI major Factions were paying Upkeep for their units, but the Minor Factions (think Civ VI's Barbarians and City States combined) don't seem to pay upkeep and 'spawn' units at a ridiculous rate - very similar, unfortunately, to Civ VI.
Humankind will be different. In fact, a lot of Civ VI players will doubtlessly complain, in so many words, that it "isn't Civ" and therefore familiar in its mechanics and depictions. This is short-sighted: we've had the Civ Version of 4X historical for years, the complaints about it have filled digital volumes of posts on this and other Forums, it is past time to try some new things in the genre and see what works differently, or (again, as I've posted elsewhere in this Forum, along with many others) what can be used, modified, assimilated or 'massaged' to make the next iteration of Civ better . . .