The report I read was from the Pakistani government and was intended as a rebuke to the US. They had every reason to make the figures look bad.
My essential point is that drones seem to be efficient. I'm not arguing that their deployment is at all justified, merely that they seem to be rather more clinical than conventional methods.
The big advantage of large Reaper-style drones is the zero risk of casualties for the attacking side but it also poses the temptation to use them more frequently. I think that has already happened in Pakistan and Afghanistan and, soon, in other parts of the world. Even if they are more efficient, more of them wil be used so the net benefit for civilian safety is difficult to assess.