I had the funky dreams with Chantix, some REALLY wild ones, but the only time I got nauseous while taking it was after the first week when I went to the full power doses and tried to have a cigarette...
IMHO that's partially how it works. Last cigarette I had was 3 days into the full dose regimen, had half of it, puked my guts out and threw the rest of my smokes away.
And it definitely worked well (For me!) a month after quitting I was working on an oil rig off the coast of Africa, needed a place to stage the servers I was working on; they put me in the smoker's lounge.
...and I didn't have or even want one.
(To each their own and all that, I get that too!)
You might be on to something with the nausea. I can remember many times waking up after a long night out and not wanting anything to with smoking which would last a good part of the day. Just the thought of a smoke would turn my stomach.