Taking my flu shot for the first time

I'm 28, never had a flu shot before.

Not because i don't believe in them or afraid of them, i just never bothered taking one.

Now my office are encouraging everyone to take them, and i decided to go for it specially that i live in New Zealand and its flu season now that winter is starting here.

So what should i expect? For a first timer. I heard some people develop cold like symptoms, some have arm pain for a while, some people develop some sort of an allergic reaction to it and so on.

I'm perfectly healthy with no allergies but i thought it would be good to hear from those who take it regularly.