This is perhaps one of Shakespeare's more interesting plays, if you will. In comparison to Macbeth it isn't quite the walk in the park.
I think conceptually it enables the reader to see that characters can influence characters to such a degree that the original traits are masked and changed. Tragedy in this play is definitely a main component - and a great emphasis that perhaps the villain doesn't always find their true defeat. In a way, wasn't the "villain" successful? He lied to everyone and pretty much killed whomever got in his way.
Here, Iago's purpose becomes plain; he sees that Othello and Desdemona's marriage is less than solid, and seeks to use his powers to break this marriage apart. Iago is again "honest" about his intent, but only to a person whose involvement will help him greatly. The words "honest" and "honesty" appear repeatedly in the play, used primarily by Iago, or in reference to him; ironically, Iago is the only person in the play whom Othello trusts to judge who is and is not honest, and the only one whose integrity is not questioned until it is too late.