Apparently these weapons (called NE or "Novel Explosive") are a variation of Shoulder Mounted Assault Weapons currently in use. These new weapons use "Thermobaric explosions" which set fire to the air by injecting a fine, flammable mist that ignites in a massive fireball and pressure wave strong enough to collapse a structure. The mist will travel around corners, making it particularly difficult to control or escape from. In addition, anyone not killed or crushed in the initial concussion will die from asphyxiation as all the oxygen is sucked from the surrounding air.
These weapons have already been cited by Human Rights Watch as inhumane and "comparable to low-yield nuclear munitions". HRW also has an unpleasant description of exactly how anyone caught in such a blast would die (comparing it, unfortunately, to chemical agents).
Larger versions have been used as "bunker busters" in the past. The significant thing here is that they are now being used in urban settings where it is difficult to control and "virtually impossible for civilians to take shelter".
When you combine this with the previous news on the chemical weapons nature of "White Phosphorus" use, it looks even worse for U.S. military ethics.
Just when you think you're going to peg your Outrage Meter, you discover it has a logarithmic scale...