I have to disagree vehemently. It vastly depends on the speed that you are traveling with on your bike. As soon as you aproach the upper 20s (km/h, European here) it is way too dangerous to be traveling on the side walk. Here in Germany we have dedicated bike lanes which unfortunately mostly run on the side walk, meaning that pedestrians often do not look up to check if a bike is coming. More dangerously though are the cars taking right turns, because even if they bother to look you will be right in their blind spot. Add to this cars coming out of driveways or sidestreets, only bothering to stop and look once they reach the actual street and you get quite a dangerous mix.
Whenever it is allowed thus, I always ride on the street and counting the number of close calls or accidents I had it is a lot safer. Basically the only danger when riding on the street are butthurt drivers who make it a point to overtake you with a 10cm gap even if the opposite lane has no traffic, because you are supposedly occupying 'their' street.