Rock-hard (and indeed contains various rocks such as gravel), never goes stale, and is terribly sustaining. A traveller can go for miles, just knowing there's dwarf bread in their pack. A traveller can think of just about anything to eat rather than dwarf bread including their own foot and even pumpkins (see
Witches Abroad).
Various forms of dwarf bread can be used as weapons, e.g. battle muffins and drop scones. Fine specimens of dwarf bread can be found in the Dwarf Bread Museum, Whirligig Alley,
Ankh-Morpork, open to the public whenever volunteers have time (
Feet of Clay). Dwarfs away from home often miss dwarf bread very much, and complain that mass-produced breads by Mr. Ironcrust hardly meet the standards, but dwarfs are too busy working to go and see the exhibits in the museum, much less to volunteer there.
Proper dwarf bread has to be not just baked, but forged (with gravel, of course) and dropped in rivers and dried out, and sat on and left, and looked at every day and then put away again. For preference, its use as a cat's litter box is also recommended. Dwarfs generally devour it with their eyes, because even dwarfs have trouble with devouring it any other way.