SK880 user,
thank you for asking my opinion
From a medical point of view, vaccination against influence (flu) is strongly adviced for people who are at particular risk, like children or elderly people, because in these two categories the immune defences are supposed to be less effective, compared with young or mature subjects. For this reason these are the categories that are more susceptible to complications, sometimes fatal.
Vaccination is also adviced for health care providers, who work in close contact with a great number of people who are often ill and, for this reason, are exposed to a greater risk of infection.
For all the other categories, the choice is a personal one and has to be weighed against the risk of contracting the illness: since the influence virus is diffused by air (most often through small liquid particles like the ones we expel when we sneeze or cough), it's easy to understand why a guy like Al, who commutes daily to his working place in NYC and maybe travels in a crowded train, has a greater risk of infection compared with someone like Bluezplayer: they live in the same state but their habits are quite different!
Re. the issue of live vs. dead viruses, it has to be said that, even when live viruses are inoculated (or inhaled) they are "weakened" beforehand and thus the risk of introducing them inside the organism is comparable to the use of dead viruses.
Finally, speaking of side effects, the most significant is a slight malaise (comparable to a mini-flu) that usually last two or three days (the time-interval the organism needs to develop its immune response).
Okay, that was all, I guess; if you have more questions, feel free to ask and...
...have a safe winter!