
Cunning compares rather poorly with generic skill cards like Perception and Unexpected Courage. It is decisively inferior when it gives a bonus of only +1 or +2. Even if it were to give a bonus of +3 all the time, I would think the card was maybe too good, but not by a large margin, it would still depend on what I thought was best for the deck. So in order for this card to be even average, it has to have a + 3 bonus most of the time. Meaning your deck has to be spending the great majority of the game with ten plus resources saved up. That means that Cunning can only be used in the type of deck which is specifically built around saving tons of money.
I have played that kind of deck and I find Cunning to be a perfectly useful card in that deck. The funny thing is that even in the deck which it is specifically designed for, I don't always include Cunning. It is good, but not so good as to clearly outweigh the value of other good cards I might be considering putting in the deck. It ends up depending a lot on how much I think that particular deck really needs a good skill card that gives both an intellect and an agility boost.