Where I live, just about all of the downtown streets are one-ways and it does wonders for getting around both on foot and in an automobile. Though the latter will be more punishing if you don't know the lay of the land, and there will be congestion near on-ramps during rush hour.
In my experience, some types of one-way streets are some of the least trustworthy for crossing on foot because drivers treat them as race courses or interstates with speed limits (and sometimes worse, traffic lights) as barely a suggestion. It's interesting how much excitement as a pedestrian I find at the elimination of one-way streets and replacement with calmer two-way street "diet" patterns. (Street "diets" reduce lanes, add more dedicated turn lanes, smarter medians and parking.)
