Often there are two types of comments on things like this: the people running around and screaming and those who insist nothing is as dangerous as anyone ever makes out. Credit to The Reg for attracting more reasonable readers! On the other hand, the comments are more interesting than the story in this case...
There is no doubt about it - this machine is a torture device, there's no way around that. Prolonged pain with apparently no side effects. Well, there certainly are. Aside from the fact that the likelihood of cancer is cumulative with time, and therefore this gun like all radiators of EM energy increases your chances of disease, it physically heats your skin in order to cause pain. Just like being microwaved briefly, or touching a hot object.
So sure, assuming it isn't the blast that knocks a DNA strand in one of your important cells, you are likely to recover from any burning or boiling that it might cause you, just like you would after an accident in the kitchen.
The operational scenario is likely to be one where people get a few quick blasts, recoil from the heat and all is OK. But if someone tries to run away, and accidentally runs in the direction that the beam is sweeping, or the operator gets a bit trigger happy, the burns caused could easily lead to loss of fluids, shock and even death. And that's just burnt skin. If the burns run deep, who knows how much damage could be caused. This could well be targeted at someone's face.
What's more, where in the Western world does a crowd hostile enough to warrant such a weapon ever accumulate!? Surely this was only ever designed for war-torn countries, or are riots anticipated by the powers-that-be, perhaps due to the legislation they wish to pass that removes our last human rights?