Single point of attention, but inherent in the system takes the "feet" in the son especially purposes. And stops. Sometimes trying to cross obstacles and mini gets stuck. Virtual walls can prevent such inconvenience by making him avoid certain areas at risk. And also for the return to base, sometimes of evil in a large area to find the way. Strategic placement basis in this case.
Try especially with the drop in prices on the net.
Really no regrets buying. PS: my children have dubbed "Wall-E"!