For a tourist, the Schengen Agreement is more important than the EU region. Traveller doesn’t need to go through the immigration check.
I travelled to Croatia in 2007. Even though Croatia didn’t join both the Schengen and EU, there was no immigration. I worried I couldn’t get the stamp.
Anyway, I hope other Former Yugoslavia countries will join the EU following Croatia and the world would become peaceful.
¶Although Croatia on July 1 has become the European Union’s 28th member state, the Croats themselves, as a whole, are far from jubilant about this historic step. It is, however, a step with a signal effect. […] ¶From an economic point of view, the EU is now shouldering a new burden by taking Croatia into the fold. […] Full text is here. Referenced from Deutsche Welle, 1 July, 2013