The war didn't really end, it just stopped. There was no permanent peace deal or treaty, both sides agreed to a cease fire, one that has now been in place for almost 57 years. The lasting impact this has is that both countries have to invest heavily in their militaries to guard the border against the possibility of another war. The DMZ, or Demilitarized Zone is a two mile wide stretch of territory between both countries that is both one of the most heavily mined and heavily patrolled pieces of land on Earth.
The US has had to maintain a permenent military presence there, and recently, it was admitted that for a time, we have kept nuclear weapons there as well, something that did not go over well with the South Korean public.
North Korea has never recovered from the war, and so much of its budget today goes towards military spending that the country is largely without power, adequate food or energy supplies.
The lasting impact that this war has had is that the countries of North Korea and South Korea continue to be enemies. They continue to be divided and North Korea is constantly doing aggressive things. Just recently, they allegedly (they deny it) sank a South Korean naval vessel.
The US has been impacted because we have to maintain a large number of soldiers in Korea to protect the South from the North.
As for how it ended, it ended pretty much as it began. The border of the two countries is just about exactly where it was before the war started, so no one gained anything.
There are so many ways to answer this question. Let me take it from a few different perspectives. First, the country was split in half and now they are two different nations. The Northern part is communistic government and the South is a democracy. Second, many families were divided and that is still the case today. We need to keep in mind that there are many living relatives separated today. Third, from an economic point of view, the North has lagged behind incredibly so. They deal with food shortages and all sorts of hardship, whereas South Korea is a booming country with a great economy. Think of some of their companies - Samsung, Hyundai and Posco.
The Korean War technically did not end. It is still going. Both sides are still at war.