I dont think she was nice or mean. Once we got a better view into her character, it seemed that her main concern was the safety of her son and husband. At certain points in the story, it seemed that she really could have cared less which side won.
In DH she went along with Harry faking his death so she could get back into the castle to make sure Draco was safe.
But does this make her nice? No I dont think so, but is she mean? Not really.
Its a pretty tough call.