In my experience, it's nothing like as simple as that... a friend brought up on Anglesey pronounces eu as eh-u where the u is like the German u-umlaut. Other people from only a few miles away pronounce it almost like 'eye'.

Reminds me of the friend of a friend who spent all day wandering round Wales looking for the village he could see on lots of signposts- Llwybr Cyhoeddus.