I used to have a hybrid (halfway between a road bike and a mountain bike) for city riding and it was ideal. Plenty of speed in a straight line with enough agility to take corners and tight turns no problem. Sturdy enough to take rocky, pot-holed filled roads and to go up and down gutters and also cut across grass with ease. In the bush they are fine on standard trails but are somewhat awkward on steep, twisty trails.

Road bikes are fine for getting from point A to point B in a city but that's about it. They are very limited to where they can go and if you do go off road with them you're guaranteed to buckle the rim within an hour and then it's off to the bike shop to get it straightened out.