Pillars of Eternity is relatively bug-free compared to Obsidian's previous offerings, but it all depends on who you ask. Players who've experienced a certain game-breaking bug that sees all character passives reduced to zero might not be so kind towards the game.
So here's what's up: do not double-click items to equip them to your character. Drag them instead.
What happens if you double-click items to equip them in your inventory? Your passive, racial, and permanent buffs disappear. Seriously. If this happens, you'll have to reload an older save. If you're unlucky, you might not notice what's happened until you've made significant progress through the game.
Here's a video of the bug in action, as posted by TrueMenace on the Obsidian forums.
Should the bug strike party members, you can remove them from the party and add them back to resolve the problem. Unfortunately, this fix only works for party members and not the main character, so you'll have to wait for a patch to clear things up if it's affecting your main character and you'd rather not reload an older save.
Obsidian's Adam Brennecke writes, "We do have a fix for this, and I'm trying to make it retroactive, so it will fix any save games that have this problem."
Stay tuned.