I haven't seen this film in a while, but the ending disappointed me. Throughout the film we were given her struggle over her beliefs, sense of duty and coming to terms with her pregnancy (i think, can't quite remember very well). The end where she goes to press the detonator then drops it spoilt the whole thing for me. A far better ending IMO would have been her hovering over the button and then leaving us to decide whether she would have pressed it. This would, I feel, have forced us to think further into the film, watch it again maybe, work out what she would have done.
Don't get me wrong though, this film was great as far as i remember, very engaging.