Most of the time I couldn't see it and it was behind piles of dirt or on the other side of a hill!
Well this is according to what this promising technology makers propose! they say you can form a commandant and undless slaves XBee's to extend the control radius that is possible offcourse and i think if it was a fool technology no body would have employed it that much as we see these days into their projects and its too costly that's why too.
I use RF 433 Mhz transmitters or Transceiver modules but i think they are till now very nice utlities given their price and range but turn off;s are those irresponsible communication that it makes.