IV, delta, Gamma, Theta have to be watched. VIX is watched by those that trade anything related to s&p. If you're trading MSFT options, then you should watch MSFT IV. And not just the month you're exposed to but the whole term structure. I recommend you read Baird's book...it's eye-opening
VIX is good enough to get a general idea of how implied volatility is moving in the options universe. But, as has been mentioned, the IV of your specific investment is more important. Mark