It's flat and - at least north of the Blue line - there's good infrastructure. Combine that with dense population, and the lake and tons of parks nearby, and it's the best biking city I've ever lived in.
Snow is hard to bike in (I think, I dunno though, being in coastal California).
I’m sure it would feel like a lot to you, but Chicago doesn’t really get a lot of snow or ice. Prevailing winds in the winter are out of the northwest. The majority of the moisture picked up from Lake Superior gets dumped on the Upper Peninsula and Wisconsin before reaching that far south (Lake Michigan moisture is dumped in western Michigan and northern Indiana).
Biking infrastructure in Chicago is good in wealthier areas and pretty bad in poorer parts. There is definitely an element of unequal funding, but you have to understand that Chicago’s municipal system of government puts a lot of power at the hands of the alderman - they are like little mayors of their wards. If the people in a ward want bike infrastructure, the alderman will find the money for it. If the people in a ward don’t want to give up car lanes for bike lanes, it’s not going to happen. And that’s how they feel in the poorer areas. There have even been instances of bike lanes being removed in some neighborhoods!
I'd still be terrified of using a bicycle in Chicago. I never realized how many people almost never look at the road while driving until I had such a good view into their cars (yes, cyclists and moped riders are watching you). The only thing that alerted people to my presence was the rattly 30-year-old two-stroke engine under my ass.
TLDR is the simpler you make a road, the faster and less attentive drivers are. While a complex cobblestone alleyway might be very tricky to navigate, basically no one will be killed there because you wouldn't attempt to speed while looking at your phone on it.
Neither of those are options driving in a city of any size.