Managed to beat it.
The final boss didn't do anything but spawn a crabman every few turns. It had over 9000 HP but no sound effects. The two part gauntlet preceding it had like 20 crabmen with guns, two queens, a half dozen sirens plus some artilelry in an arena consisting of a corner and an open area. I killed all the crabs with mind crush in a single turn after they piled in after me (regular killing spree powers wouldn't have worked due to the return fire) then killed the rest once they all panicked. Then you fight a bunch of artillery aliens that shoot actual bombs instead of critters, (that was the first time I saw them shoot their load since before that I always focused them down before they could fire, turns out that was the right decision)
I can see what the game trying to accomplish but it's constantly being brought down from being good by various issues, mostly the fact that it's unfinished and it's desire to copy NuCom without regard for how it melds with its mechanics;
Actual Line of Sight is a good thing, but it's stapled on top of NuCom cinematic movement and animations without consideration for whether it will work or not. So you have to deal with not being able to choose where your guys can crouch and whether they can peek out from behind a wall or not. Waist high cover seems to only be used for protecting your legs (so make everyone wear the barely armored sniper pants I guess). Overwatch is a fucking joke, besides being able to pick a cone of fire you have the same "open fire as the alien moves in slowmo" deal, so now you can miss since the cinematic moment let the dude get behind cover. Oh it's resolved in sequence instead of all at once so the second soldier in line might not even get to shoot of the alien is out of sight.
Compare this with the much less cinematic Silent Storm; you still get some fucky moments but it's much easier to deal with it since everyone stays still and you can crouch or go prone wherever you want.
Instead of researching everything yourself, you have to ally with the factions to get all the cool stuff. Problem is the faction system kinda sucks;
Rep management is very simple, it goes up when you defend a faction's bases and attack their enemies but goes down when you attack them or save the bases of the other factions (once their rivalry starts heating up). There's also a gimmick where the rep won't go up past a certain point until you do a mission for the faction to level up their relationship but if it goes down you won't lose the benefits of the relationship. As I said in an older post, the mission can spawn on the other side of the globe so you might be forced to wait a long time before you can be friends with a certain faction.
Faction bases seem to be clustered in one region of the world so depending on where you spawn you'll see constant alien raids against one faction while the rest go unnoticed, in my game even once I explored everything the aliens kept attacking one faction while rarely touching the other ones.
The "meta" thus boils down to focusing on an alliance with the factions whose havens keep getting attacked, then once you're allied, keep raiding them to please their rival, ally then betray them in turn to befriend the last faction. I don't know what happens if you let an allied faction's rep drop too low since I managed to keep them topped up thanks to alien bases.
Oh and there's neutral havens, they don't do much besides offering you a side quest you can complete for extra resources.
There's very low map variety, there's randomization in some of them but it's barely noticeable, most maps are also very small so it's easier to notice when the pieces start repeating. Guess they had to copy that from nuCom too.
There's stealth. It gets broken when you combine the assault's killing spree power with the stealth guy's double damage from being in stealth with the weird detection mechanics that let you stay undetected even as you're blasting fools with a shotgun.
I'm too tired to go into combat and the but the gist of it seems to be a trying to focus on crowd control where you can choose to permanently remove an enemy by killing it, cripple it by shooting it's arms off or make it panic by killing other enemies or use "nonlethal" tools like psi or stun weapons. When it works it's fun and challenging but then you get enough dudes to level 7 and unlock the death god powers and it becomes more about killing everything in the first few turns instead of trying to survive against overwhelming odds. The game seems to be build around this since it throws more and more enemies against you as it goes on, culminating in the final mission I described above.
Edit: Oh yeah, and I played on hardest
Just watched a clip and noticed that on the lower difficulties you have like 4 enemies per mission instead of around a dozen, that might change how you play the game.