European Union is successful or a failure?

European Union, an economic body formed as a consortium of 28 european nations with a unified currency euro should bring welfare, development. But unfortunately it has been failed to control eurozone crisis, failed to control the economic hardship of Greece, spain etc, started overshadowing the sovereignity of the nations, started interfering into non economic activities, imposed sanctions on Russia on crimean issue. Thereby it has been regarded as the new sick man of europe by the critics ( as we know we used yo refer turkey as the sick man of europe).

What do you think weather the European Union is successful or a failure?