Haven't played Port Royale but it's not as good as the new XCOM.
I'd suggest to rent it first when you're unsure.
To be honest: The game is decent but it's certainly not the best game. I just liked the idea of quite a reimagining of Gangsters and I liked Mafia (thank God I didn't get Mafia II for Xbox^^) so this was a Must Have for me anyway - maybe you check out Ohm's LP on YT if can't rent it.
World First to 1000/1000:
Omerta - City of Gangsters (02/1/13 - 05:40pm GMT)
Completed retail: 33