You know, I'm just not really that impressed by Beliefs or Instincts. (People tend to clump them in with Traits in some sort of "OMGORZ GAME MECHANICS" trifecta, but really now, Traits are nothing new.)
(I predict that right now many readers, such as Daniel, will be yelling at their computer screens, or possibly throwing things at them. If you aren't you might want to start. It'll be cathartic.)
Beliefs are good, I guess. They're a mega-Flag. I like Flags, at least on a theoretical level.
Instincts are okay, but there's issues. For one, the idea of Instincts-as-Action-Macro gives some a mechanical edge, ("When suprised, I draw my sword" gives the owner a number of free actions, which is quite advantageous in Fight!), but there's no hard and fast guideline for what's a legal instinct and what's not.
(Example- an instinct "I always hit him in the head," which would ignore the standard wound-targetting system. More powerful than many of the instincts given as examples? I don't think so. Legal? Certainly a legal die-trait, but I don't know if it's a legal Instinct)
But what it's really about, is what I'm looking for out of Burning Wheel, and that is Exploration of System. BW's got a massive, massive ammount of System to Explore. However, when you make characters and go from spending skill and trait points to picking Beliefs, you've jumped from Exploration of System to Exploration of Character, and for every character I've burned up this has been like suddenly shifting into reverse while going 60 down the freeway. Unless I had some ideas already in mind, it all just stops and chargen shuts down.