Personally, I thought that Facebook had peaked around IPO and would slowly go irrelevant.
a financial advisor would always tell you to unload all shares at each vest since you are holding more shares in the form of future vestings.they would then tell you to diversify it into ETFs in a mean variance optimized portfolio tailored to your risk appetite using standard deviation of historical returns and correlation of underlying basket of goods. this is a solid approach that produces predictable safe returns.
I would rather let it ride since I have insider information at most companies I work for and have a better understanding of future returns on that stock that the average person on the street.
I say, take average advice, receive average returns.
:)