It is especially suited to urban warfare because the shock wave can penetrate underground bunkers and shelters.
Victims are killed either by the force of the blast wave, or by the subsequent vacuum, which can cause their lungs to collapse. People on the edge of the blast wave may suffer internal injuries like burst eardrums and ruptured lungs.
The bombs are not explicitly banned under the Geneva Convention on warfare, though the convention does require signatories to use proportionate force and avoid killing civilians.
In other words, they're rather nasty, though limited in scope.