what reputation does it have for people from all over Poland and what do you associate that city with?
The reputation is neutral or positive. I know they have a nice Old Town. In 1980s I spent there a few days, attending an international folk festival.
I can see it is still held today.
ro.com.pl/w-olsztynie-rozpoczynaja-sie-miedzynarodowe-dni-folkloru-swieto-tanca-muzyki-i-spiewu-potrwa-do-soboty/01460879