I've generally avoided the flu shots - I'm another that tends to react to them, so if I get the shot, I'm guaranteed to feel cruddy for a couple of days. Given that the relatively few times I've had a case of the flu I felt cruddy for maybe a day or two longer, it's never seemed like a great tradeoff.
OTOH, my father-in-law is now a regular visitor to our place. Since I'm now in regular contact with someone in the higher-risk category, I'll probably go ahead and get one next season. The mercury scare refers to a preservative used in multi-dose vials to prevent bacterial growth (thimerosol), and contains far less mercury than my remaining amalgam fillings. The MSG is used as a stabilizer in some vaccines, to prevent environmental factors from making the vaccine less effective - and it's a naturally occurring compound that's been unfairly blamed for "Chinese Restaurant Syndrome" for ages, despite multiple double-blind tests, one of which had only one reported reaction (and that was to the placebo...). IMHO, the anti-vac crowd is no more scientifically literate than the anti-smoking crowd - and often less so. But to each their own.