XCOM 2 sucks due to one system and one system only. Everything else about the game is great. Unfortunately, it's held back by the way enemy spawning works.
When one of your units gets close enough to an unseen "pod" of enemies, that effectively spawns those enemies, causing them to enter combat. Those enemies immediately get one free movement action and will then act on the next enemy turn. It sounds like a fine system, but it carries with it a bunch of incredibly unfun implications.
First of all, it means you're CONSTANTLY playing around this mechanic, with every single movement decision you ever make prioritizing the risk of spawning enemies above all else. Spawning new enemies with your first soldier's action on your turn is great. Spawning new enemies with your last soldier's last action basically means you lose on the spot. You have to constantly be mindful of never sending anyone too far from your other soldiers and never sending anyone too far ahead of your first one or two movements. The problem with that is... it means your actual tactical options in nearly all situations are incredibly limited. I quickly learned that trying to flank enemies on most maps (unless making use of very specific mechanics like a stealthed unit) is beyond pointless- you get a better chance to hit if you get lucky, but if your flanker bumbles into enemies they just die on the spot.
This mechanic was present in the previous XCOM game and incentivized just slowly and methodically moving your squad through every map without taking any risks. It was kind of a mess, though the game was ultimately still pretty fun. XCOM 2 tries to spice this up by adding time limits to missions, which is sort of a good idea but doesn't really fix the core problem. It's still suicide to try to do anything remotely clever, you just have to make sure you're moving your squad EFFICIENTLY now. They also tried to balance the game a bit more by making classes (including the special DLC ones) that specialize in close combat WAY stronger, which is nice, but doesn't work too well in practice. Yes, if you get a soldier with a shotgun directly next to an enemy they'll pretty much one-shot it, but the act of doing so risks extending your vision far enough that you'll just spawn more enemies, throwing the risk/reward ratio off.
Once you understand these systems the game isn't all that hard (though it's generally much, much tougher than XCOM 1 which is nice) but it's often just.. boring. So often I felt like I had ideas for what I wanted to do, risky or interesting maneuvers to take advantage of the terrain, but had to nix the idea because it involves moving in such a way that I might spawn enemies and die on the spot.
One last unrelated complaint- the randomness adds interesting variance and emergent situations but I've always been baffled by games of this nature that are weirdly unwilling to just give you a 100% chance sometimes. If you actually do manage to get one of those close-range soldiers up close only to find they have a 91% chance of hitting and then they miss and die (because they're at close range and in danger) it just feels so arbitrary and pointless.
Edit: There's actually another massive problem with the game- the base-building meta-progression stuff. It's mostly just kinda uninteresting, but the real problem with it is you have to complete research projects and whatnot without knowing what their results will be, but (especially on higher difficulties) you can REALLY screw yourself by not getting the right tech within the right timeframe. This means either trial-and-erroring your way though and potentially losing a run because you fell behind or just looking up a guide or something. It's not inherently problematic to lose a run because you failed to manage your base properly, the problem is the base management is boring- I'm in it for the tactical combat, I don't want to lose because I didn't have foreknowledge that it's a waste of time to perform an autopsy on Glup Shitto and you should instead prioritize building the Blowjob Factory.
When one of your units gets close enough to an unseen "pod" of enemies, that effectively spawns those enemies, causing them to enter combat. Those enemies immediately get one free movement action and will then act on the next enemy turn. It sounds like a fine system, but it carries with it a bunch of incredibly unfun implications.
First of all, it means you're CONSTANTLY playing around this mechanic, with every single movement decision you ever make prioritizing the risk of spawning enemies above all else. Spawning new enemies with your first soldier's action on your turn is great. Spawning new enemies with your last soldier's last action basically means you lose on the spot. You have to constantly be mindful of never sending anyone too far from your other soldiers and never sending anyone too far ahead of your first one or two movements. The problem with that is... it means your actual tactical options in nearly all situations are incredibly limited. I quickly learned that trying to flank enemies on most maps (unless making use of very specific mechanics like a stealthed unit) is beyond pointless- you get a better chance to hit if you get lucky, but if your flanker bumbles into enemies they just die on the spot.
This mechanic was present in the previous XCOM game and incentivized just slowly and methodically moving your squad through every map without taking any risks. It was kind of a mess, though the game was ultimately still pretty fun. XCOM 2 tries to spice this up by adding time limits to missions, which is sort of a good idea but doesn't really fix the core problem. It's still suicide to try to do anything remotely clever, you just have to make sure you're moving your squad EFFICIENTLY now. They also tried to balance the game a bit more by making classes (including the special DLC ones) that specialize in close combat WAY stronger, which is nice, but doesn't work too well in practice. Yes, if you get a soldier with a shotgun directly next to an enemy they'll pretty much one-shot it, but the act of doing so risks extending your vision far enough that you'll just spawn more enemies, throwing the risk/reward ratio off.
Once you understand these systems the game isn't all that hard (though it's generally much, much tougher than XCOM 1 which is nice) but it's often just.. boring. So often I felt like I had ideas for what I wanted to do, risky or interesting maneuvers to take advantage of the terrain, but had to nix the idea because it involves moving in such a way that I might spawn enemies and die on the spot.
One last unrelated complaint- the randomness adds interesting variance and emergent situations but I've always been baffled by games of this nature that are weirdly unwilling to just give you a 100% chance sometimes. If you actually do manage to get one of those close-range soldiers up close only to find they have a 91% chance of hitting and then they miss and die (because they're at close range and in danger) it just feels so arbitrary and pointless.
Edit: There's actually another massive problem with the game- the base-building meta-progression stuff. It's mostly just kinda uninteresting, but the real problem with it is you have to complete research projects and whatnot without knowing what their results will be, but (especially on higher difficulties) you can REALLY screw yourself by not getting the right tech within the right timeframe. This means either trial-and-erroring your way though and potentially losing a run because you fell behind or just looking up a guide or something. It's not inherently problematic to lose a run because you failed to manage your base properly, the problem is the base management is boring- I'm in it for the tactical combat, I don't want to lose because I didn't have foreknowledge that it's a waste of time to perform an autopsy on Glup Shitto and you should instead prioritize building the Blowjob Factory.