After tax pay better be higher in Zurich... it's one of the most expensive cities to live in, especially as an ex-pat, in the world (and considerably more pricey than SF.)

are you swiss? how easy is it for a foreigner to work in zurich?

I was in the London office (until a year ago) and led an engineering team spanning London, Zurich and New York. The majority of Google Zurich's engineers are not Swiss—elsewhere from Europe, from across Asia and many from the US.