Chicago is by far one of the best cities I've visited yet! I've been over 3 continents and over 100 cities and 30 countries. This is by far one of the most amazing for: food; people; location; weather; culture; theatre... I could go on. You could say that these are all great about NYC aswell, but the difference, I find, is that Chicago is cleaner, less busy but still has that gorgeous big city vibe but without all the GOGOGO attitude and it has personality. I'll be coming back for sure.
Insider Tip:Avoid the subways during rush hour ;) Try planning a bit before or a bit after, for whatever your destination purpose may be (dinner, lunch etc).