My commute is short and about half-flat, but it hits a couple of main roads. It's all downhill on the way to work, which is nice for the sweat factor. I live in the city, so I don't have to worry about coming from the suburbs or anything like that. I have two major intersections about which to worry, but people are so unused to seeing cyclists out commuting in Columbus that they give me plenty of room, especially if I ride a bit aggressively and look people in the eye as I go through the intersection. I haven't even had a close call yet. I live in a very good part of town for commuting - stores are close by and there is a major bike path that runs north-south very near me, for if I need to go a long way. My work commute is east-west, so I have to take surface streets on that route. But all in all, in a city where not driving a car is anathema, I do pretty well.
I have started a bike commuting website for Columbus at http://bikecolumbus.blogspot.com - please stop by if you live in the area and would like to participate!