I had never played this game before, but the rulebook was one of the best I've ever read, which is a huge compliment, because there are a lot of rules to this game.
Unlike many games that have a lot of rules, though, this game is balanced so well that you feel like you can choose so many different strategies and still come out victorious, which keeps individual players from getting a lead and running the table. If they are winning, you just change your approach and mess up their plans.
This is not a casual game, though. If you have players who struggle to remember rules then you will be in for a long game. The rules are ultimate logical and intuitive enough that most semi-experienced gamers who want something a little deeper than what they're used to should have a blast.