I have one, he is almost 7 years old now, and I love him to bits. he is good as a guard dog, very loyal, and it is said they are one-person dogs.
he is very good with people around me, but I am boss/Mam, he is calming down a lot as he gets older. You have to be quite strong with them especially with dogs, grump are much calmer and more friendly as a rule.
Having said all that I would not let my guard down with him. He is fast.
he likes to watch my girls, but I will not let him try to scare them, so he is now relegated to the front of the house. unless I am there to watch him. I think he would be more hurt than anyone if he did harm them, but I don't want to take the chance. Very bright and wonderful companion. lol... he is snoozing by my feet at the moment. I think he knows I am talking about him. lol....hiding his face. Ohh and he does not like cameras.
Enjoy your dog and train them well and they will reward you every day.
Jena.