Wow, no wonder this one is usually left out of Herge's canon of works. Granted this was written towards the end of colonialism (1930s), it is still pretty embarrassing. The portrayal of people from the Congo is only a very tiny step away from drawing them as apes. However, mostly Tintin spends most of his visit to the Congo shooting any animal that moves (and even dynamiting a rhino). Fortunately, the world has come some way from then and all of this stuff looks as shocking as it actually is. In terms of plot and drawing, pretty average.