In my opinion - it will take a fair amount of time before the "Culture" in general changes.
From my experience of Portugal - I would say that EU money will most likely be spent on improving the infrastructure, particularly the roads (and that will be welcomed with open arms by the majority of the population). I imagine that prices will rise in the holiday areas on the coast first, and will be led very much by the measure of "if and when" BG adopts the Euro.
Assuming that this goes ahead (and I confess to not having any real idea of how close this scenario is) - prices will definitely rise. However, if the majority of the population doesn't have the income to accommodate the increases; then the sale of goods will drop again, and rise more slowly after that.
As to general attitudes, I can only say that the people of a country change only slowly - and the Portugese people I knew prior to EU entry haven't changed much at all in their attitudes. They do tend to moan about prices - much as I recall doing when Britain went decimal! Oh dear - now I've given my age away!