Richard Nixon was a bad president to begin with as he was just a power-hungry guy who would do anything to get the presidency. His domestic policies were better than foreign policy only because how he dealt with Vietnam was abysmal. Nixon's problem was that he was president at a very unpopular and uncertain time, and his power grab with Watergate simply made everyone upset.
Richard Nixon is always going to be remember for the strides he made in foreign policy. When he took office things were a mess with the Vietnam War but he worked hard to make the best of it and brought out troops home. He paved relations with both China and Russia, two powerhouses at that time.
Richard Nixon was good at foreign and domestic policy. However he made a lot bigger contribution to foreign policy during his time as president. Nixon was able to open up a gateway to China, worked to help the issues with Vietnam, and set up better relations with Russia. None of those tasks were easy.
Nixon is remembered for ending the Vietnam War and normalizing relations with communist China. He was also a successful leader domestically, at least until the Watergate scandal. Nevertheless, most of his major actions were in the international sphere. Nixon was heavily dependent on his long time adviser, Henry Kissinger, who helped him with most of his foreign policy decisions.
China is the high point of Nixon's legacy, something that even his harshest critics don't begrudge him today. While Kissinger is almost always considered to be Nixon's driving force behind his foreign policy, Nixon's legacy will be opening up relations with China - both for the US and for China.