Here is a photograph of the Matterhorn from the south east. I do not know its source, but I extracted it from here.
There follow screenshots of the Matterhorn, from the south east. The photograph viewpoint is slightly further away and south of the screenshot viewpoint, but it still serves as a good comparison.
Shot 1A, from Google Earth, taken in April 2006. The totally inadequate topographic base turns the Matterhorn into a range of gentle hills. The default Microsoft FS2004 terrain mesh is no better, and the FSX mesh is little better. Even meshes that use SRTM data, interpolating to fill the SRTM no data areas, are little improvement because such an area blacks out almost the entire Matterhorn.
Shot 1B, also from Google Earth, but taken in January 2007 following a major terrain update.
Shot 1C, from Microsoft Virtual Earth. The mountain shows up better than on the first Google image, but the underlying terrain model does not do justice to the mountain; it is stunted and there is no western shoulder. There is some good local high resolution imagery, but high resolution coverage is patchy, and the white areas that can be seen on the screenshot occur frequently in this area. I am unable to figure out how to get the image to fill my screen.
The next three meshes are taken from Holger Sandmann's mesh screenshot comparisons. Click here for links to more of these.
Shot 2, from a "Lago Terramesh". This is a considerable improvement on most other meshes, but the shoulder on the western ridge is missing, and comparison with the photograph shows that the twin summits, which should be more rounded, are not accurate. The west summit should not be visible from the screenshot angle. I think that this mesh is based on classified DTED-1 data from the US military that somehow leaked out. Other screenshots show that it makes a complete mess of the Jungfrau summit and does seriously inadequate justice to Austria's Grossglockner.
Shot 3, from the 3 arc second data files on my DEM page, created from accurate topographic mapping. This shows up the west shoulder, and the single (east) summit which alone is visible from the angle shown.
Shot 4, from the 1 arc second data files on my DEM page. The topography is similar to shot 3. For a more clear cut example of the difference between 3" and 1" data, see the Aiguille du Géant page.