I think its worth it. When I bought mine they gave me reference pages with GPS coordinates for each guzzler. Once I get to the coordinates I can usually spot the guzzler.
Guzzlers are a water storage tank partially buried, covered with a slanted corrugated roof. Rain water, snow and condensation travel from the roof into the tank. One end of the tank is accessible to wildlife. Bird guzzlers are fenced and big game ones are more open.