Difficulty curve of this game is retarded, if you're playing on Classic, the first missions are 10x harder than even the final one....
It's because of retarded proximity spawns, retarded move once shoot once turn system, lower and arbitrarily limited by "research" squad size and an emphasis on experience as opposed to equipment as a primary source of soldier power.
I mean sure, having classes and specialization wasn't a bad idea, but the execution sucks and often feels too arbitrary. I mean "dense smoke" on supports, how the fuck does that even work? My soldier kills xenos and suddenly develops the ability to make more and denser smoke with the same smoke grenades? Or battle scanner on snipers. Why the fuck can't I make and give my soldiers scanners as I please but need to wait for some arbitrary experience threshhold on a specific soldier class?
In good old X-COM your ability to fight aliens was limited primarily by resources. You did bad you lost out on funding, alien resources, troops and possibly equipment. You could afford to see the soldiers die like flies as long as the mission was at least a Pyhrric victory. They were expendable, sure experienced ones were a bit better but most of the soldiers power came from equipment. Which brings me to my second point.
The tech progression sucks, that is it is essentially a +stat one rather than one opening up new gameplay possibilities with few exceptions. The shifted half of the gadgets into XP unlocked abilities due to the dumb decision to dumb down inventory management. Then you have HP bloat with brick walls of HP bars over the heads of heavy muttons and other late game xeno fodder. Rather than have armor mechanics and counter them with more reliable weaponry while still making a potential penetrating shot lethal they turn to HP bloat and MOAR DMG.
At the same time alien weapon damage doesn't change much but player HP increases with armor (armor grants HP and medkits restore HP! The wonders of technology!). It is supposed to be offset by the fact that enemies now have more HP. But what you end up with are drawn out firefights between two blobs of HP that make Blobert's avatar look like he has anorexia (if he didn't change it from that lovely kwan blob of living fat he had).
Then you realize that enemies spawn only when triggered by the player so as long as you stay put there is no danger in such a firefight if you have enough HP. You shoot them, they shoot you, lots of margin for error and lucky crits don't mean much. Zero tension. In the one true X-COM *every* shot could end with a casualty, from start to finish in Cydonia. You could still lose your flying power armored bros to fucking sectoids in those Martian pyramids, the same gray fuckers you faced in the very beginning of the game. They didn't need a screen of HP point markers to be lethal. Tech ensured that the enemy wouldn't get as many chances to actually shoot, just as tactics did. The margin for error was thus far lower than by XCOM's endgame, while still noticeably higher than when you face the alien menace armed with assault rifles, firecrackers and X-COM t-shirts in the beginning of the original game. Balancing difficulty with just HP and DMG is plain retarded.
Every damn flaw of this game is a consequences of the same shitty dumbing-down decisions, the difficulty is no exception.