The satellite imagery of the flooding in Pakistan is insufficient to grasp how widespread the devastation is, unless you zoom out enough (which you can do at the MODIS page). The imagery focuses on the flood plain of the Indus River: it covers most of Sindh province and a good chunk of Baluchistan. See The Washington Post’s maps for perspective. The Earth Observatory and MODIS pages, as well as the CNN article, have before/after image sliders: Earth Observatory compares the situation to three weeks ago, the other two to last year.

Update, 1 Sept:

The ESA has released the above image based on Copernicus Sentinel-1 data. More than a third of Pakistan is now under water.

Update, 3 Sept: The Guardian has more before/after imagery.