I do not have a G6, but I have owned 2 pontiacs in my life- and both have been horrible. I swore I'd never own another one after the first. 10 yrs later I was convinced to try it again, and car #2 is just as bad.
First car was '96 Grand Am. The radiator hose exploded on the expressway halfway back to college and left me stranded (car had about 60K miles on it at the time). Maybe a fluke. But then the cooling fan constantly went out- the wiring, whatever. It wouldn't run, car would overheat. Literally left on the road stranded with that thing on 4 separate occasions.
I now own a 2004 Grand Prix GT. Bought it used w/ about 35K miles on it. It now has approx 50K miles on it (owned it for about 1.5 yrs). In that time the 'ABS' light went on. Followed by the traction control light. Took it in and there was just a disconnect in the wires. Nothing actually broken, but another wiring/computer issue. THe check engine light has currently been on for about a month and I havent' taken it in yet. I'm sure it's a sensor or something minor. But that stuff adds up. Look at catguy- power steering issue. Megan, crappy moon roof quality. It may be minor, but it shoudln't happen. I had an accord w/ 120K miles on it when I sold it and not one issue. Literally. I had oil changes done, brakes when needed, and set of new tires for that thing. Maybe it's just be, but going from the honda that wouldn't die, back to another pontiac that has had it's stupid little issue, I'm done w/ pontiac.
So my opinion of pontiac quality is very low. The engines are known for being good. It gets good gas mileage- but I just find it very unreliable. However, it's paid for and is our 'extra' car for running around town, so I'm stuck w/ it for now. However, this time I swear- I will never own another pontiac EVER.
Also- girl I work w/ had a G6, 2 door- she liked it, but said it was horrible in the snow. Traded it in for 4wheel drive b/c said she was all over the place. But that's 2nd hand info.