They are so kind and affectionate when you get to know them and are extremely loyal. These beautiful creatures are protective of threats and can analyse based upon your expression if you are worried and then they will let out their protective streak.
Not only are bull mastiffs great guard dogs, they are also brilliant with children (e.g cheer them up, make them feel safe/calm, help with mental disorders etc) if bought up properly.
Mastiffs are sometimes portrayed as being aggressive and violent but are only like that if trained to be. Lots of mastiffs get abandoned and have to live in kennels, that can sometimes cause their loving attitude, because they are thankful of you for changing their lives.