How did the speaker of "My Last Duchess" describe the person on the wall?

The Duke's none too kind about the last duchess, whose portrait he shows to the Court emissary. But then, he did have her killed, so that's hardly surprising. By way of justification for his deadly deed, the Duke proceeds to give the emissary certain details of the late duchess' personality which place her in an unflattering light.
For one thing, she was too easily pleased. Almost everything she laid eyes on—whether a bowl of cherries given to her by a courtier, a sunset, or a white mule she used to ride around the terrace—caused her to speak words of approval, even blush sometimes.
A further problem with the duchess, according to her widower, is that she thanked everyone for whatever they gave her with the same degree of enthusiasm. The Duke was sorely offended by this alleged slight, as it put the 900-year-old name he'd given the duchess by marrying her on the same level as the very humblest of gifts. And for the Duke, that was nothing short of insulting.
Yes, the duchess always used to smile at the Duke whenever he passed her, but then, she used to smile at everyone else too. Once again, the Duke was being treated the exact same way as those he considers his social inferiors. More than anything else, it was this alleged outrage to his sense of propriety that convinced the Duke to have the duchess killed.
https://www.poetryfoundation.org/poems/43768/my-last-duchess