We're about to renovate our bathroom, and currently the toilet is behind the door. It's a very small bathroom, but we've never found a problem with this positioning. Our neighbour (who's house has the same layout) however, thinks it's terrible. She says her boys are always flinging the door open which then bashes against the loo. We don't have any kids, but our first is on the way.
So should we be looking to move the toilet? Bearing in mind it's much easier to keep it where it is, and so far we've not had a problem with it.
We could just switch the way the door opens, of course, but then the first thing you see when you open it is the loo, which probably isn't a good idea.