Is Pillars of Eternity's style of interaction more like Diablo or is more like the Ultima series?
There's a bit of depth to this question but the simplest comparison might be through mouse interaction: In Diablo if you click the mouse, your character automatically moves to said location or attacks. Additionally, there's limited world interactivity and more emphasis on fast progression through a storyline. In later Ultima games the left mouse button was used for interaction/"hands", and the right mouse button was used for movement/"feet". Additionally, many of the objects you see are movable, destructible, combinable, stackable, etc.
Thanks,
CS