When the attack first happened, they showed families still taking their children to the park and the kids playing happily. Later, they showed the empty park. You really saw the hopelessness and that there really was not much to go on for after that.
I remember renting this movie sometime in the '90's. After the era of nuclear war panic films had passed. I had wanted to see what this genre had to offer. Not only was this movie the most hopeless film I'd ever watched I had to force myself to watch another movie in order to continue my hobby of film consumption. That's how bad I felt after watching Testament. I wasn't sure I could watch another movie - any movie, any genre. Happily, I enjoyed whatever I next viewed. Maybe it was a raunchy comedy? And I found my way back.