The Sontarran Strategem
I really really love Donna. She's utterly brilliant, though it's frustrating it's taken until year 4 for something so brilliant to come along.
But, yeah, Helen Raynor? Who is she fucking to get these two parters that she seems so capable of fucking up? Maybe it's Davies' continual interference that has turned the 10th Doctor into something so preachy and deeply unlikeable, but I don't think so. She writes the Sontarrans in a way that seems ever so slightly off, while Martha comes across all to often as a simpering whiner.