Arguably the best in the series, it certainly gets my vote. The plot is basically the same, you are a young man whose father figure was a hero and it is your job to fight a corrupt empire. Other than that the story is almost completely different, it takes place on the same land mass so some of the story bleeds over and a few characters play a part in both games. In Suikoden 1 you wind up fighting your father but in this game you wind up fighting your best friend.
What I like about the Suikoden games is there is a lot of optional stuff, you can recruit over 100 people to your cause but most of them are completely optional. You can also collect hammers to raise your weapons to their maximum level but this too is optional and is really only useful if you want to mash the action button to quickly get thru random battles later in the game. But there are a ton of other optional things like cooking ingredients, paint for murals, music, all kinds of things. There are also mini-games where you can win collection items or equipment that will help you progress in the game. One way to make money in the Suikoden universe is trading, you buy something in one town and sell it somewhere else where there is a demand for it. You can even recruit someone at a point in the game who will make it where you can travel instantly to any town you have been to and back to your castle.
The battle system is the same as Suikoden 1 you can have 6 people in your active party. You get a lot more control over the flow of army battles in this game versus the first. The duels are pretty much the same. I like the look of the castle better for this game as well but I can't seem to find any good images of it.
All in all its a pretty good game that stands out from the typical RPG. This is also available on PSN fairly cheap.