The "problem" of difficulty is a difficult one (heh), because to new or casual players, the game is really hard. If you're a veteran or someone that has done lots of extra reading, you can just cheese or min/max the game. The balance will be for the game to be fun, yet challenging, to the average player.
It's likely that Larian will target classic mode at the average player and tactician mode at players who want a real challenge.