The whole Gall-Peters thing is idiotic. Modern global wall reference maps all use non-cylindrical map projections like Robinson and Winkel Tripel, not Mercator. It's a solution in search of a problem, and has problems of its own, precisely equal in magnitude to Mercator.
There's nothing inherently wrong with Mercator, it does exactly what it is supposed to do. That it was used for general reference maps was probably a bad idea, but that was a poor choice of projection for the task, not any sort of inherent flaw in the projection. Gall-Peters is no better though. Where Mercator distorts area, Cylindrical Equal Area (Of which Gall-Peters is just one parameterization) distorts angles. The hybrid maps like Robinson and Winkel Tripel strike a balance, which is why they are used for general reference maps. When a true equal area map of the globe is needed, Mollweide or Hammer are far better options, or if you absolutely insist on a cylindrical equal-area projection, Hobo-Dyer at least doesn't look quite as ugly as Gall-Peters.