The story does make you question who the real enemies are. We would initially say the Hath (especially after they kidnapped Martha) but as we delve deeper into the story we learn that it is the war-like Cobb, who defines military victory, genocide and peace as the same thing. He is neatly contrasted by The Tenth Doctor's pacifism (the problem is though that with the knowledge we have now of the events of The Day of the Doctor, we realise a lot of what he says in this story is wrong).
There is a very much a classic series vibe to this story with the two warring factions and our heroes being split up, being taken to each others camps (Genesis of the Daleks springs to mind). Donna comes across well in this story as well with her solving the mystery of the war, just leaving the character of Martha. She is personally my favourite companion under RTD but was poorly served by series three, as in all but about two or three stories The Doctor is reminiscing Rose, preventing any proper friendship to come about between them. I am therefore glad for her return in series four with her character being used here to highlight that the Hath are not the monsters of the story.
The whole story climaxes in an epic final confrontation with hints of the Timelord Victorious starting to show but The Doctor has not gone that far yet and instead uses the pain at the loss of his daughter to establish peace and build up a civilisation based on the values of 'a man who never would'. It is shame that Martha has to leave at the end of the story personally (some may disagree) but I realise that it is necessary for her to go as any further stories would hinder the development of the character of Donna. Overall this seems to me a very strong story but does not have the something which could turn it into a great.
8/10