As has been posted above, the city climate -rainfall especially - varies widely upon which part of the city you live in. Someone up in Canyon Heights can expected uninterrupted days (weeks, sometimes) of winter rain and gloom, whil someone in Tsawassen will see a lot more sunshine.
Overall, though, the winters here are not very unlike Seattle, Paris, or London.
The people who experience the severest winter problems are the one with
SEASONAL AFFECTIVE DISORDER, or "SAD." This has found to have neorochemical causes and indeed is triggered by insufficient exposure to sunlight. If you suffer from this, plan ahead and arrange for medical light treatment.
Otherwise, packing an umbrella around for a few months of the year is certainly much easier than wasting a weekend digging out you driveway!
We all hope you enjoy your stint in Vancouver