People I met were nice and all but also felt conservative/boring (not many flashy people on the streets) - I didn't find any interesting meetups when I was there either.
I'm a huge Blues Brothers and Ferris Bueller's Day Off fan so I was doubly disappointed :(
I'd be happy to learn that I just did it the wrong way / had bad luck and all the cool folks are somewhere else.
As for the murder concern, other commenters (tptacek in particular) covered that.
Regarding the "murder concern" it was more like being seriously disturbed by it.
The downtown area seemed safe enough for me to stroll around also during night time but waking up to a news reporter somewhat happily announcing that the doctors saved the baby whose pregnant mother just became victim to a drive-by shooting in south Chicago the evening before is just.. I don't know, fucked-up shit like that doesn't happen (often? ever?) where I'm coming from. All in all there where 5 dead and 43 injured over that weekend alone. So that clearly played a role in my remarks regarding Chicago and my feelings towards staying there.
I hope you do get another chance to visit. I haven't gone there in a few years, but I have good memories of the city.