I've had the first round of the Astrazeneca one.
It did not hurt at all (barely noticed it).
My upper arm felt quite bruised a couple of days later (like it had been punched), although any pain went within a week. Had a headache for a day or two.
I very much wanted to get vaccinated if the option was able to. I fear spreading the virus to loved ones, also fear getting "long covid" and having long-term damage to lungs etc.
I think my only fear of getting vaccinated itself was the military-style operation of it all and not wanting to put a foot wrong.