That one would even ask this is scary!
Well ... a completely unelected Executive making laws for one. A completely unresponsive government - they do make some neat laws, but they are fully elitist, they have a total disdain for anything populist.
A system wherein there is 'no way out' i.e. they will punish anyone who leave (i.e. Brexit).
Have a look at Junkers statements regarding the Treaty of Lisbon referendums. Those words should have sparked a revolution, and he should have been jailed long ago.
If there were alternative systems to the EU, for example, a trading block that was powerful enough to counter the EU i.e. UK, Norway, Switzerland ... then people would see that they don't have to be 'pro EU' to be 'pro European' and there would be alternatives.
The EU is one country away from having to face this, because Norway, Switzerland and UK are not quite strong enough, but with one more ... then we'd see some kind of alternative.
There would be 'competitive federalization' models and people would then have choice.
Right now, it's a dictatorship of the elite, and there's no way at all to get the Executive branch to budge on any issues.
Even literally voting 'no' on the Treaty of Lisbon was not enough. You can literally vote them down and they will march forward with their plan.