Positive: Design, Gameplay, & Depth. The game is balanced quite well for how many features it has. Court for internal politics, diplomacy, royal guards, space and ground forces, ete. It looks simple at first but the internal workings of all the features really make it complex ( in a good way).
Negative: If you lose all members of a faction in the court system you will have got hit with -20% to the economy and the only way to fix it is luck. You have to try to kill as many members of the court during imperial meetings and hope you get at least one member of the dead faction. It always ruined the game for me.