They're a mixed bag, but nowhere near as competent as people think they are. The CIA spent 50 years trying to assassinate Castro, until a natural fucking death got him. And we've got the best intelligence agency in the world. That's the best we've got to offer. 50 years to kill a single man, and we still failed.
Fact of the matter is intelligence work is tricky to begin with, and trying to leverage intelligence into action is harder by an order of magnitude.