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).
Far left appears to have that firm ass, welcome to San Francisco, crisp sourdough crust. Far right is some bread pan, Texas toast make’n, sponge crust.
As always, the left of where the fun is, and the right boring and conservative.