An extremely entertaining film that can be watched over and over again through the years. This is due not only to the riveting action-packed sequences, but also to the plausibility of the story. For example, the primary objective of the mercenaries and of the men who hire them is absolutely believable. In addition, the revolting atrocities that the real-life Simbas perpetrated are not shied away from in this film (a more graphic description would have been impossible in the 1960s; even today, it would command an X-Rating for the almost unbelievable violence that was, as a matter of historical record, committed -- e.g., young children raped in front of their parents).
There are some negatives, to be sure, not least of which is the indifferent direction and mediocre acting. Jim Brown, in particular, is almost embarrassingly bad. And the ending, without giving anything away, is certainly disappointing -- self-righteous and silly.
Still, "Dark of the Sun" is a most entertaining viewing experience, and I strongly recommend owning it. In addition, I suggest having the Wilbur Smith book on which it's based as a companion piece.