Expert is silly. It just hides information from you (like the effect radius of your spells, really?).So, Pillars of Eternity on Hard difficulty with the Expert and Trial of Iron modes on is, uh, a bit challenging
I didn't play through on Trial of Iron (because generally in a game like this you shouldn't expecting to be winning all your fights, if its a first time play through), but I played through on Hard and was honestly kinda underwhelmed. Had a rough streak near the beginning (that underground temple in the first town x_x), but that aside basically all of the fights in the game went super smooth. Even the last boss.