Interesting. I never thought she was an evil character at all. She might have been pitched as the TNG villian of the week, but I felt she was fairly complex. Her line, "People blame the military for the wars that we are asked to fight. But I think it is your kind, Major, that will be the death of us all," put her in a different light for me. She was perhaps a loyal and obedient soldier who will fight when asked but she strikes me as being weary of war and the toll it exacts.
Agreed, I actually found myself sympathising with her predicament of being a conscientious and principled officer tired of being manipulated by others, typically the Tal Shiar but in this case our own Deanna Troi.