This game is quite possibly one of the finest and most in-depth strategy games that exists. It's very much one of those "just one more turn," kind of games, and once you get the hang of it, it'll suck hours of your life away.
Pros:
Really fun.
Really nuanced strategy with genuinely challenging scenarios.
Cons:
To get the full experience, the expansions are absolutely a must, which can get a little expensive.
The UI, like most Paradox games, is a daunting and terrible beast at first. It will overwhelm you initially, and you will need to adjust to the fear it strikes within your heart. Don't worry, with time this shall past.

In summary, 10/10 would buy again.

I still agree with this review five years later.

I STILL agree witht his review 6 years later.