Everyone needs an IW (and those who have owned one will know why I say that). My last one was the friendliest creature God ever made. I only saw him angered once - he was sneak-attacked by a Labrador. After being knocked off-balance by the attack (and having the soft tissue of his nose cut), the IW regained his balance, led with his shoulder, flattened the Lab, and within 2-3 seconds had the Lab in full submission pose and was standing over him threatening with the ugliest growl you have ever heard. I, the Lab and the IW knew that if the Lab made one wrong move, he was dead. I told my friends to imagine the turn-around here, imagine that I walked up behind Mike Tyson and sucker-punched him. From that point on, I have never under-estimated the lethality of an IW. Anything that was bred to chase down and kill a wolf one-on-one has immense capabilities.
However, the fiercest IW that has ever walked would stand no chance again an adult Alaska Brown Bear in a one-on-one fight. A determined pack of IWs could but even then the IW pack would take casualties.
The giants are usually the sweetest. My wife who grooms professionally says that among the friendliest clients are two St Bernards, and A Newfie.