From a purely selfish point-of-view:
The EU and the acceptance of the "federalized" euro currency has ruined one of the benefits of foreign travel in Europe. The strong Euro has messed up perfectly good exchange rates; especially in Italy. When I was in Italy in 1999 (when the Lira was still the national currency), my dollar went much further than it would now that Italy has the Euro which is currently stronger than the dollar. I'm being both sarcastic and serious here.
From a global peace point-of-view:
The EU is certainly a good thing, which hopefully, in the future, will prevent the massive destruction brought in Europe over the past two centuries.