As far as the sappy ending, I'm glad the Speilberg sticks to his guns. It seems that people these days want down endings, but he doesn't care, and does it his way.
I think people want realistic endings, one fitting of the film just viewed. We had just watched 90 minuties of the human race being exteminated starting with big cities like Boston. Everyone was on a run for their lives, and here are four people who looked like they just stayed at home and watched the caos from the windows. Definately a questionable artistic decision, but not a questionable studio decision. I'm not arguing that the familiy should have died, I just think they could have at least showed that they had gone through hell too. I expect better from Spielberg.
Overall I liked it though, very intense for me.