On the face of it the use of drones seems a great idea. Eliminate the bad guys with no risk to friendly forces, little collateral damage and at relatively low financial cost.
The trouble is every time one mission goes slightly wrong, and the collateral damage includes women and children (maybe the target's family, maybe just his neighbours) the incident acts as a powerful recruiting sergeant for Al Quaeda and the like.
Overall is their use ultimately counter-productive, particularly in Pakistan, where a moderate politician (in Pakistani terms) like Imran Khan has come out vociferously against them? It's no good trying to win the hearts and minds war in the area if a misguided Reaper strike undoes all the good done.