EU3 is deceptively easy but once you try and play it is not easy at all. It has a sheer cliff-side as a learning curve. HoI3 is a simpler game by far. EU3 requires a lot of knowledge about how it works before you can play and the interface is a mess. Most mechanics of the game are not explained anywhere except on the separate wiki which you therefore need to have open if you are still learning the game. And there is an incredible amount of mechanics to learn. This makes EU3 also a very rewarding game to play but never call it simple.
As I said before my most anticipated feature would be a better distinction in settlement colonies and trading posts.