Given that his description is "a slap in the face to the typical humorless qunari", I think it's guarenteed he's going to have a sense of humor. I think it probably won't be quite as low-brow as Oghren or Isabela, but it's going to exist.
I think a big part of Iron Bull having left the qun is he's going to have thrown off all the shackles they put on him. The qunari are supposed to keep theirselves very disciplined; Iron Bull is going to be a creature of the moment. When he's angry, you're going to know he's angry, when he's happy, you're going to know he's happy, and when he's in love, you're going to know he's in love, because he's going to actually have a spine and tell whoever he loves how he feels instead of cowering like a child and having his friend do it for him.*coughAveline*cough*.
I'm sorry, had something in my throat; I said Aveline.
At least that's what I'm hoping. I'm hoping he's going to be like the literary Conan the Barbarian in that respect; that he'll be tough, that he'll be a badass, but that he won't be guarded with his emotions.
I think that would be a good contrast to some of the characters we've had before, and likely some of the characters in this game. I see Cassandra as being the one who'll have more difficulty expressing her emotions.