Don't take this as being too lazy to Google; I was hoping to hear some anecdotes about acclimation or something.
I am Venezuelan and before coming to Canada the coldest I had been was 12 Celsius. In my first winter, I was living in Sault Ste. Marie which have a twin city of the same name in Northern Michigan. That meant snow at my hip level everywhere and temperatures that reached -40 celsius.
I am living in Toronto area now, and the winter is very milder in comparison. Long story short, I do have funny stories but the main thing I have learned is that human body is able to adapt easily even if you have been in hot areas for a long time.
If I could do it surely you would too :)
There are local sub climates like anywhere else of course, so if you're living on the far east coast, or next to the west coast mountains, you'll get worse and better climate, respectively.
My wife and I went to the US southwest a few years ago. When we left LA it was a bearable 115F (dry as a bone). We got home to 21C and had to start the AC because we couldn't breathe - it took us a day or so to reacclimatize, it was so humid.
You also left out how windy our Ottawa winters can be, and how much snow we can get (cf, e.g., http://ottawa.weatherstats.ca/metrics/snow.html)
There's a reason we invented humidex and issue so many wind chill warnings.
(Ottawa is one of the most beautiful cities ever, and was recently ranked fourth most livable city in Canada by MoneySense, after Calgary and two suburbs of Edmonton. Not bad for an urban area of about ~1M with sticky hot summers, frigidly cold winters, and some of the most aggressive drivers ever (we really do need to chill). It makes up for these with a splendid natural setting, ready access to nature and the arts, and only one major source of pollution, the car.)
I must be one of those aggressive drivers because I can't believe how slowly everyone seems to merge onto the 417 :)
"Ah, soul mates", she said, sighing and shaking her head.
(All three of us complain near ceaselessly about how poorly our neighbours navigate the rounabout we've had nearly a year. The ones who stop in the middle to let in others nearly cause apoplexy.)
I'm from the mid-Atlantic, and I think the weather there was generally "nicer" than it was back home - the Summers aren't as hot & humid and the winters aren't as harsh, but there tends to be more rain in the Pacific Northwest than the East Coast.
It gets cold. Very cold. This can be handled, as other commenters have noted, by dressing appropriately.
What is harder to handle is the length of the winter. Somebody joked about the winter going from Nov - Mar. That's a good year. On a bad year, expect Nov - May. It affects everything, no matter how well you dress for it. You have less sunlight in the day to be outside, if you happen to have a good day for outdoor activities. Friends are less willing to go out (there is lots of "hibernating"). You become more reliant on cars and buses if you can't walk everywhere you need to go. If you own a home, enjoy shovelling the driveway sometimes 2-3 times a week. If you're susceptible to depression, it can be particularly brutal.
As for surviving winter, the Scandinavians have a proverb that goes "There is no such thing as bad weather, only inappropriate clothing." It gets cold, but it's nothing that can't be handled by proper attire and/or a warm car (heat isn't optional, although air conditioning is). Also, in Montréal, it's also technically possible to never go out, as the underground city[1] has connections to residential buildings, commercial buildings and office space.
Victoria has probably the best climate in Canada but there's not much work there. Vancouver has stuff going on but it's rainier and occasionally gets cold. For a few days each winter, it will drop below zero and in most years there is a dusting of snow although it doesn't last long. Schedule this period (basically January) as vacation time.
Of greater concern is that Vancouver is expensive and rental accommodations are subpar. Forget about buying a house unless you are rich. The transit infrastructure is mediocre and the city is plagued by terrible architecture and a general blandness. This is offset by the tremendous potential for outdoors fun: skiing, sailing, rock climbing (in nearby Squamish), etc.
In Vancouver, there are a few days a year where there is snow, and everyone is almost as surprised as you would be by it, every time. Other than that, it's very unpredictable, even within a single day. It's normal to have multiple periods of drizzle and sunshine in the same day.
If you require heat, go elsewhere. We had some anomalous heat this summer but it pretty much never gets truly hot. By east coast standards it's sort of in perma-spring.