Depends on what exactly you mean. Namib and Namibia are not synonyms, the former being a desert along the west coast of the latter.

Given the size and diversity of Namibia, a single safari can't possibly suffice, unless it lasts six month to a year. A six day jaunt by train can obviously not even begin to scratch the surface. Just properly exploring Etosha would require that much time.

The Desert Express is certainly not expensive though, and it may well show you enough to whet your appetite.

Johan