Do Iago succeed in his plan? If he does, in which way does he succeed?
Ultimately, Iago plan apparently does not succeed. On the other hand, I believe that Iago feels disregarded due to the fact that he in spite of being held in high esteem does not get recognition in form of a good position as lieutenant. In consideration of this, Iago succeed in the sense that he manage to get heavily influence; he is no longer overlooked. Hence, it is a victory in itself that he has managed to get that much influence; he that possibly has been disregarded through parts of his lifetime. When taking a closer look at his character, he is disregarded by the senators whom does give a damn about him. And above all, Othello gets the position as a General being black, and besides, he obtains Desdemona as well even though he is much older. So my conclusion is that he in some sense succeeds with his plan by getting a sort of confirmation of his significance by being that much trusted and not disregarded.