The Panmunjom Peace Treaty gave the PRC nearly everything it wanted with the exception of control of Formosa. This peace probably would have been accepted earlier by the Communists, but Truman, a Democrat, could not afford to offer such a peace to the Communists, since the Republicans would have attacked him for being "soft on Communism." Eisenhower, a Republican, could get away with it, since his own party did not attack what actually was a fairly conciliatory peace agreement.
Although it ended the war and restored an uneasy peace to Korea, the Panmunjom treaty was a failure in many ways. After three years of fighting and 4 million dead and wounded (including over 50,000 American combat deaths), Korea remained divided into two armed camps just as before the war. Furthermore, the treaty and the war did almost nothing to bring the Cold War closer to an end. US-USSR tensions were as high or higher after Korea as they had been before.
The war was disastrous for Korea as well, destroying most of its industrial plants. North Korea, despite its mineral and hydroelectric resources, fell into poverty and couldn't keep up with South Korea's economic pace: South Korea soon boasted a GDP (Gross Domestic Product) quadruple that of North Korea. North Korea did, however, remain fairly independent of USSR and PRC influence. And in fact, Chinese and Soviet squabbling over who should pay the bill for the Korean War was one factor in the Sino-Soviet Split evident later in the Cold War.
The Korean War, as a terribly negative experience for the United States, and as the initial significant military encounter of the Cold War period, seems as if it should have provided the US with an object lesson of the nature of warfare in the Cold War era, and the impossibility of keeping that war limited. However, the US made many of the same mistakes in the Vietnam War, in which the US yet again backed a corrupt southern regime against a Communist-Nationalist northern regime that effectively fought a guerrilla war. In Vietnam, once again fighting a non-industrialized country, the US nevertheless employed strategic bombing to an even greater extent, not surprisingly with little result. Had American military and political policymakers considered the lessons of Korea, rather than the lessons of World War II and appeasement, they might have avoided the Vietnam quagmire.
The Korean War had a further legacy as well, not the least of which were the 4 million deaths claimed by the conflict, including 50,000 American soldiers. But as the first war that the US entered and did not win, the Korean War demonstrated to the US that though it had emerged from World War Two as a superpower, it's desires and will were neither inviolable nor imminently achievable. In its ambiguous, unvictorious ending, the US encountered a new, and even frightening outcome in war, and this outcome helped define and solidify future American Cold War policy. Perched as it was during the opening of the Cold War, the Korean War stalemate, full of sound and fury, served less as an object lesson than as a prophecy of what was to come.