The poem is ironical and reveals its rhetorical sense, gradually. His flowery speech confuses and disguises any possible motives, however, and the mystery is left unsolved. Though there are some select few that are shown her portrait, she cannot speak for herself.
In terms of meter, Browning represents the duke's incessant control of story by using a regular meter but also enjambment where the phrases do not end at the close of a line. It demonstrates this, as there is no interruption from the servant and no break whilst the Duke is talking.
Your time is important. Any type of essay. The poem conveys the controlling nature of the Duke by the use of one stanza in the entire poem. They appear very controlled, just as the Duke appears through his described mannerisms.
His irony goes even further when he reminds the envoy that he truly wants only the woman herself, even as he is clearly stressing the importance of a large dowry tinged with a threat of his vindictive side. Further, the duke shows an interesting complication in his attitudes on class when he suggests to the envoy that they "go Together down," an action not expected in such a hierarchical society.