Most addictive game ever made
This game has been out, in some form or another, for probably 15 years or more...it's definitely not the new kid on the block. But it's just as addictive as ever. The relatively simple gameplay allows you to jump right in, and keeps you coming back for more. You just seem to want to go after one more galleon, one more buried treasure, or sack one more town. With 100 different endings, 5 different factions, and being completely open ended, the replay value is just incredible. And as soon as you finish one game, you're going to want to start another as a different nation, trying different ships, in a different time period, trying different ships, etc.
The PSP version is probably 90-95% of the game that came out on PC and XBox. A few things are missing, but nothing that's gamebreaking. I miss the map that you could superimpose over the sailing screen...you have to keep hitting "start" to bring up your map and access your status menus. Also the encyclopedia is gone, although some of the menus have item descriptions. And I kinda miss not being able to change out the flags and sails that you're flying...although capture ships retain their originals sails and flags, so you can still fly whatever you want, depending on what you capture. Also, you are stuck with whatever cannon a ship has when you capture it...so if you get a frigate with less than 40 guns, you're just stuck with it.
The game was implemented pretty well, also. There are a few loading spots that last a few seconds, and at least one load spot which kinda breaks immersion for a second (when you beat an enemy captain, it goes to a loading screen between your winning sword stroke and the surrender cut scene). And I noticed at least one glitch in the land battles, but it doesn't actually affect the gameplay.
Overall, if you liked the other versions, you're going to love this one, also. Since I picked this up on eBay (at a steal, yay), nothing else has been in my PSP.