I wanted to second what Oguz-Han Ince wrote.
I own an Anatolian shepherd and he is exactly as he described. There is no better guardian dog in the world.
I would add that these dogs can live up to 15 years and are not fully mature until they are 4, and it's the nature of the breed to be wary of strangers and very protective of its "flock".
Once they get to know you, they are as friendly and playful as can be, but it can take time.
And as the previous poster said, these dogs are very intelligent. Mine has figured out how to turn the door knob with his mouth and pull the door open, so if I have to leave him in the house I have to deadbolt the door.
Mine would also jump the fence occasionally when he was younger, but as he matured he became satisfied with patroling the perimeter and then finding the highest spot with the best view to keep watch.
These days I can even leave the gate open and he won't go out unless I call him out.
Anatolians require little to no training for their guard duties, it's the socializing part that requires a lot of work. But it is well worth it. When I have Nicodemus with me I feel pretty safe no matter where I am.