One blog that I wrote last year gets endless requests from young students asking for help in writing essays about democracy pro or con.
The issue can only be handled by breaking up the term democracy. To argue democracy pro you need to pick a model you like, such as the U.S. Constitutional republic with the executive and legislature separate and government powers widely distributed geographically, or the Japanese-English model of a multi-party legislature where the executive is derived from the legislature. The con argument on these countries is that America was a basket case for thirty years because of a baby boom population that resisted an unpopular war. It was only cured by an external attack that unified the country. Japan (and Mexico) were stuck with one centrist party for forty years.
There are many bad examples of democracies under dictators such as Palestine under Adolph Arafat, the Soviet Union for eighty years and recently Iran under the council of Mullahs. There are failed democracies: Algeria, Chile, Turkey, Venezuela, Pakistan and Argentina where democracy was used to install dictatorial regimes and overthrown by the military.
There are plenty of ambiguous examples, for pro or con, where we have extreme democracy such as India, Switzerland and Israel. India and Switzerland have the problem of democratic inertia. Israel has the problem of surviving against monstrous external enemies when some of the enemy's relatives live in Israel. Israel has an Army that needs clear goals and public support to protect the nation -- very difficult in a democracy.
Lastly, I wrote a book on true democracy. True democracy requires true representation not the horrible biased group of self selected people generated by elections. True representation requires a legislature based on a random sample of the population. This has only been tried by the citizens of Athens. I believe that a true democracy would be a powerful and successful form of government but it would have to be tempered by some form of representation for the commercial forces of society. Such a system remains to be tried in the future.