Chicago is great city to live in. I've spent my entire life in the midwest. I've grown to enjoy the midwest culture and general friendliness of people. Life in Chicago is very familiar to those who have lived in the surrounding suburban area. The most noticeable difference between the down town area of Chicago and it’s surrounding suburban neighbors is where you’ll find the people. I’d say that most people in the city don't seem to spend a lot of time at home. Where just the opposite it true in the suburbs. Folks tend to stay home as much as possible.
Chicago is a walking city. You can walk basically anywhere. Walking 45 minutes from home to work is not uncommon at all. I'd even say that all of Chicago's public transportation is setup as an extension of how people like to walk in the city. The trains and buses are a means to move you to the next walking location.
I work in the tech startup world. Chicago’s tech startup community is small when compared to New York or the valley, but it continues to grow. There are a ton of 'tech' jobs in Chicago, but most are corporate gigs that are not all that technical in nature. I'd actually say that jobs in science related industries in Chicago are likely to be more technically challenging than most programming jobs.
When I'm not working I enjoy exploring Chicago on foot. The lake front in Chicago is great. Tons of Museums, art, music, zoos ... endless amounts of stuff to do and find.
One of the things that makes it hard for me to live in Chicago is the lack of outdoor activities. Most outdoor activities are only the city friendly kind. Sports like basketball, tennis, and biking are very popular. There are a few more expressive water sports on the river and lake. Maybe if your looking for a game of chess, you can generally find one near the corner of Michigan Ave and Randolph. Otherwise you have to go a long way to find some open wilderness.
There's a lot more to say about Chicago, but these things stick out the most to me. Chicago is a great place, I'm glad to be here.