Not for the faint of heart
The first Paradox Interactive game I played was back in 2004 with the entry of [the first] Crusader Kings and I loved it. There was something about picking a person, who was just a Count and through political espionage, marriage, outright greed and willpower advancing not only your place but that of your dynasty. If you played your cards right, you may have some competent offspring to continue with. I will say this, for those that are expecting something similar to Total War: Shogun 2, this is not it. This game is heavily influenced by the traits that your character(s) have and who their partners are, which will contribute to the starting traits of your offspring, as well as the choices you choose to and not choose to make. There are no full screen battles with tactics. Wars are won and lost through sheer numbers and the traits of your characters.
This game is challenging. While it is easy to declare war, no Casus Belli is required, if a war goes on too long or your [personal] demnse becomes too large the rebel factions (Buddhist, Shinto or Christians) may begin to rebel and take over your provinces causing you to have a war that may have ended in two years, take five or more to quell the rebellions depending on the size of your demnse and how bad they are. Also, I was surprised at how large the map seems, despite it only being a fraction of the size of CK2.
The only downside is that there is no tutorial for this game. So for some people new to this type of game, it may be difficult to completely grasp all of the concepts and it will seem like an overload. Unfortunately there is no walkthrough or direction regarding the various menus. Prior to purchasing this, I tried to see if there were Youtube videos to get a better understanding, to no avail. The only direction you will receive is to refer to the 88 page manual that is available once you download the game. With that said, I don't recall a tutorial for Crusader Kings 2, but after 166 hours in the game and never refering to a manual for guidance, there are things that I'm only just finding out.
For those considering this game and unsure if their specs will meet the minimum here are mine and it runs great.
Mac mini mid-2011
Processor 2.7 GHz Intel Core i7
Memory 16 GB 1333 MHz DDR3
Graphics AMD Radeon HD 6630M 256 MB