Recently, I bought this on Steam since it was uber cheap (around $5), but I regret even that. I bought it because it had interface improvements/bug fixes over the original Port Royale, and if it was just that, I'd be ecstatic since the first PR was so much fun. Unfortunately, Ascaron actually managed to make some key gameplay elements far worse and as such, this sequel is a huge leap back from the original Port Royale.
First, let me warn others that if you do buy the game, you must disable Data Execution Prevention (a security feature in Windows XP and Vista that make some buffer overruns ineffective vectors of attack) or else the game crashes with the obscure message "Could not find translation files". I had to find that one on Ascaron's forums as Steam's notoriously shitty customer service was of no help at all (I don't think anyone's even home...), but I digress.
The economic gameplay is very similar to the first Port Royale in that you lead a convoy (or several convoys) of ships around the Caribbean, buying low, selling high, and occasionally attacking pirates and other trading vessels. You can also build trade and residential buildings and conduct in some sim/RPG-esque quests like escorting a trader, hunting pirates, marrying a governor's daughter, etc. But the majority of your time will be spent trading goods and here, there are some great UI improvements like sliders that quickly adjust the amount to store/sell in your warehouse, showing the average cost of the goods in your hold, tons of shortcut keys, etc. Yes it's a glorified spreadsheet, but it's a good looking, responsive, and usable one.
However, on the combat side, the game is far worse than the original Port Royale. In the original, you could engage many vs many ships, ordering your ships to target specific enemy vessels. However, the naval combat in PR 2 is overly simplified in that you directly control 1 ship at a time versus many enemy ships. Gone are the glorious days of Port Royale's epic, gorgeous naval battles, where dozens of your military frigates took on massive, heavily armed military convoys of a competing nation. PR 2 replaced them with fugly, low-poly, ships and gameplay that feels cheap and unsatisfying, where your best strategy is to pick a weak but fast brig and just harry the enemy piecemeal. It's slow, it's boring, it's tedious.
Also, the designers inexplicably included an inane dueling system, which is an LMB/RMB click-fest taking minutes to complete. This is an extremely annoying, unchallenging, mind-numbing distraction that takes you away from your primary desire to trade and complete missions. It's like playing an RPG where at the end of combat, you need to click a button until a counter reaches an arbitrary number. For several minutes. Joy!
One thing to note is that the number of combat incidents is also severely decreased in PR 2, with far fewer pirates and less aggressive enemy nations so you can focus more on building your trading empire.
So it seems that the designers in PR 2 decided to make trading the key focus by completely borking naval combat. That's unfortunate because one of the great aspects of PR 1 was the ability to support your already successful "spreadsheet"-controlled trading empire with extremely satisfying and fiscally rewarding naval combat, allowing you to shape the Caribbean using a combination of your economic and military might. So if you are solely interested in the trading part, PR2 does it better but the militaristic portion is far worse in this evolution of the series, making it overall a "skipper".