It is deep and complex, deaths are final, losses are final, defeats are crushing and a lot of time is needed to understand how to go about things and not get overrun. Takes a big investment, but it's very well made and a lot of fun. If I start another game, I won't be picking a high difficulty level, that's for sure.
I wish they made a Rainbow Six type game about it, but including the planning and investing/building aspect. Maybe the FPS will turn out like that if it comes out.