It has its problems. Just look at our Presidential election. But to really understand its benefits, one has to compare it to other systems. The most economically prosperous nations (structurally sound and with a high standard of living), are democracies. What is the alternative? Can you name a one party state or dictatorship that has a bright future? People want a voice. It takes hard work being a citizen of a democracy. You have a responsibility to pay attention and vote.
You could make a case that China is an economic powerhouse. But you would have to ignore their many social ills and human rights issues. Their standard of living is still below the west.