The positives have already been talked to death, so I'll stick with my complaints.
First off, not to sound like a l33t gamer, but the game was far too easy on Tactician. I remember getting totally wrecked in D:OS1, and especially 2 on the same difficulty, but I never once even had to use a rez scroll. I can only hope the future "enhanced/definitive edition" adds a higher level.
The pathfinding is abysmal, especially for party members following you outside of combat. I wonder how much time I spent having to awkwardly switch between party members to make them individually jump over even the smallest crevices.
This one could just be a me problem. but I tried changing my character's appearance several times throughout the game, but each time he always made these stupid looking gormless faces whenever the camera was on him and he was meant to be expressing or reacting to something.
This one could be just my PC, but the loading times were painful, and even longer than the loading times was waiting for the city area around me to to go from a blank background with levitating floors with no walls, ceilings, or windows, until they got properly filled in after a couple minutes.
There's plenty more to add on later, but yeah, those are just what come to mind.