In a word: Confusing.
The learning curve is unpleasant. I played HOI2 for many hours, which is the only reason I have any clue at all how to play this game. Even so, you've got to be willing to commit many, MANY hours to getting the hang of it, let alone be any good at it.
I am confident that there are many forums committed to discussions of HOI, but I've never been interested in wading through forum posts to learn how to play a game.
So, if someone else that I know picks the game up and wants someone to play with, I'll dig back into it, otherwise this one is getting set on the shelf.