Fixed Gear vs. Road bike?

I don't make any significant commutes, just a couple miles here and there but i'd like to start biking more often. I have a decent road bike but I'm getting a second bike and i'm trying decide between a nice road bike or a fixed gear. I've never ridden a fixed gear and there's only light hills in my area and they look like they could be fun. Any opinions? How difficult are fixed gears? are they good short commuters? Any and all help is appreciated.