The big thing in Divinity is manipulating the environment to abuse environmental effects, like puddles you can electrify or oil slicks to set on fire. The first game was all about laying down a barrage of spells and abilities to cripple your enemies. Because that could get abusive very fast, Divinity 2 changed it up so that before you do health damage you have to get through either physical armor or magic armor. Furthermore, melee/magic statuses (like crippled or burning) are automatically resisted so long as the respective physical/magic armor is up. The result is that parties are now best when they focus almost solely on one damage type - physical or magic. If your swordsman is whacking on an enemy and stripped his physical armor and the enemy is close to death, you can't have your mage quick blast him with their wand as that will damage their magic armor first. Magical damage on weapons -and especially arrows- is sort of gimped because you are never doing enough magical damage with weapons to get through the magic armor so the magical effects never start applying. This is really bad for magic arrows -which are a big part of the combat unless you are packing some dedicated magical artillery- as none of their bonus effects (like charm or curse) will trigger as the arrow itself does damage to physical armor while magical effect gets stopped by the magic armor.
So far annoying, but it gets worse.
Enemies -even on normal/classic have obscene magic/physical armor, especially creatures. Human enemies tend to have a clear preference for one or the other so there are some interesting tactical decisions at least. Creatures have obscene pools of both, making combat pretty difficult. The enemies also have vastly improve battlefield mobility abilities from last game so trying to maintain a coherent battle line with mages in the back falls apart almost immediately. I slightly gimped my party because I didn't distribute stats and abilities well, but I'm having to lower the difficulty occasionally to easy. There are also fewer trash mobs to fight, which means it is harder to tell if you have a bad party set up/tactics or the battle is supposed to be difficult. Fewer trash mobs also means fewer areas to grind.