Angola carries a number of illnesses common all throughout Africa. It has rates of life expectancy and infant mortality that rank among the worst in the world, partly from poverty and partly from disease. Everything from malaria to rabies can pose a problem during your visit if you're not inoculated against them or prepared to decrease your risk of infection.
If you're looking for a crime-free trip, you're coming to the wrong place. While you can definitely minimize your chances of becoming a victim, crimes of various kinds run rampant through Angola.