Blue is a color not a breed or type
Get with it man! Damn, can't you see what s/he's trying to explain? For fucks sake stop being a troll.
To the OP, you shouldn't have to live your life uncomfortably or scared/in fear. I agree with starting off polite with the neighbors and bringing up your concerns...but to be honest, it probably would last all of five minutes with me. I understand that the dog might not be a bad dog-he really does sound understimulated and not cared for...but that doesn't make him any less of a risk. If he's really 150lbs and bored and nippy and a guardian type breed (Rotties are right?) then what do you think is going to happen when he's bored/frustrated beyond the point of being able to control himself. I would absolutely be carrying mace around with me every where I went...and I'd consider something a little stronger too (as long as it's legal)...cattle prod...taser...something.