He's a political genius, but the Nixon Administration mishandled Vietnam terribly. Chile was equally worse and not excusable. In conclusion, horrible person. I think Kissinger may have done better under a President Rockefeller (who was his mentor before joining Nixon's team) or Romney.
It's a good occasion to point out detente was hardly a novel move by Nixon and Kissinger. It's been already pursued by the likes of de Gaulle and Brandt. LBJ administration was very interested in the "new opening", but Vietnam derailed it then.
True, LBJ almost became the first sitting president to visit Moscow in 1968.