I've just finished The White March part I and I've to say I like it. Overall the new setting. In one hand I like the snowy places and the new village, the designed are beautiful. About plot, I don't want to spoiler anything so I only say that it's more worked in the core game,but I need to play part II yet for a complete opinion. On the other hand, when Obsidian said The White March will be inspired by Icewind Dale they don't lie, because in my opinion this expansion is more focused in combat, but this is not bad, because I think with this expansion you have a more complete game: plot + explotation in core game and focused combat in expansion.

My conclusion: do you like Pillars of Eternity? Well, I'm pretty sure expansion doesn't dissapoint you.