I think it depends on where you are. If you are in suburbia, where hardly anyone actually uses these serially-placed squares of cement, then I don't see any problem, as long as you just go slow and keep an eye out for kids and driveways. Even then, I'd prefer the road, since the tree roots always push/sink squares by 1/4 inch or more, making for an exceedingly bumpy ride.

In Cities, or areas where there are pedestrians galore, then the bike should only be on the sidewalk if you are at it's side, walking...