Warren's message these days is that Scott Brown's votes hurt Massachusetts, and unlike him, you can count on her to be on the side of Mass residents all the time.
Brown's entire campaign is based on the fact that he's nice, works well across the aisle, and makes people feel all tingly inside.
Warren, by linking the Senate campaign to the national level and by continually beating up on Brown on the fact that he's all about protecting the obscenely wealthy on taxes -- even at the cost of the 98% of us -- scored well on her fronts.
Brown's petulant, nasty personal attacks hurt him.
If he goes out to the rest of the debates like that, he's going to lose the election, as each debate wakes more and more people up to the fact that he's not nice at all.
One other comment
Scott Brown, during the first question at the debate:
Professor Warren claimed that she was a native American, a person of color, and as you can see, she's not.
There's something deeply offensive about Brown's notion that there should be some sort of heritage litmus test based on whether or not someone sufficiently "looks" like that ethnicity, which is exactly the point he made when he attacked Elizabeth Warren on her Cherokee-ness.
She didn't "look" Native American, and therefore -- according to him -- is lying. In a country that's becoming increasingly diverse, there's more and more interracial families. Not all of the children in those families will look like the minority (or both of the minorities, in many cases).
Is Darren Criss of Glee not half Filipino, because he looks Irish? Is Grady Sizemore of the Cleveland Indians not half black, because he looks Italian? Is Patrick Chung of the Patriots not part Chinese, or Jamaican for that matter, because he looks black?
My extended family happens to be very diverse, but it's not always clear if all you did was look at the color of their skin, or the shape of their eyes. Scott Brown's notion -- that they somehow don't get to claim their heritage because they don't 'look' the part -- is, or at least should be, a disqualifying statement for office in the 21st Century.