B.B.
Unfortunately, I don't have much else to suggest - I haven't had to battle quitting smoking, and I only know a few people who have, and when they quit, being short-tempered came with it.
You might try talking to the pharmacist - ask if it's something that's prescribed very often, if they've heard anything about side effects, if the people taking it have had much luck with it, what the most common side effects are, is there anything that can be done to offset the side-effects at all, etc. I'd also ask a few different pharmacists too.