Driving in Ottawa, Canada.
DO NOT DRIVE IN THE SNOW ON THE STOCK/BASE ALL SEASONS.
I cannot stress this enough. LOL If you get more than a bit of powder or cold temps, it's useless.
As to the OP: People swear by what they know: Blizzak, SottoZero (what I have), Hankook, get a GOOD brand of winter tire, and put 'em on as soon as the temperatures drop below about 5oC (Don't ask me what that is in oF... 47oF, maybe?) Leave them on until spring.
The all-seasons are too wide to be good in the snow (they don't cut down into it) and too hard at cold temperatures to grip the snow under them. They don't dump snow from the tread at all, and you basically roll around on snowballs.
That said, with winter tires, I had no problems until we got about 8" in one snowfall. I was skating (mostly on uphill).
Unlike a few other people, I turn the TCS off in those conditions, too. I want to be able to spin the wheels so the tires dig in, and hopefully get close to the pavement. I want to regulate the throttle/power, not have the machine do it for me, because sometimes the only way you can get going is to let the wheels spin: not necessarily at full throttle, but mild spin @ say, 25% throttle will at least get you rolling... slowly.
And that's the big caution. The car IS a handful in the snow. No one will disagree with that, especially if you are... less than gentle in your steering/throttle/brake application.
Drive careful, and smart, and looking ahead/around you, you shouldn't have any problems at all.
Again, IMO, no car that lives in areas with a real winter (temp under freezing, regular snow) should be on the road without winter tires. I wish they'd just mandate them as law, then the dealers would have to sell cars with the winters included in the price.
I'm totally dreaming, aren't I?