Adjusting to a new trade regiment will always be painful in the short term.
But many factories have moved labor intensive parts of production to eastern europe. Which wouldn't have been possible without the EU.
In Romania it's actually quite hard to buy products and services that are not provided by some foreign company. Most banks, all big shopping chains (as GP noted), lots of the food and clothes, agri-business, almost all the telcoms are foreign. As a matter of fact, even though we have our own currency, a lot of products are pretty much directly priced in euros: cars, home appliances, electronics, apartments, land, rents, utility bills. All of these go up when the euro goes up (they don't go down when the euro goes down - and the euro never goes down).
To my mind the EU was our salvation not so much because of its economic nature, but because of its political one. The free market was the price we had to pay in order to be able to travel, work, study abroad, earn real wages that we could use to invest back into our own country etc. The EU also insured a decent degree of geo-political, strategic stability. Without the EU we may have ended up like our neighbors to the North/East.