Haven't played the second one (yet) but the first one was pretty much perfect in every way. 6 man turn based combat with double and triple player combos based on party members and group position. 108 total party members to find and recruit, mostly all unique with individual personalities. As you find more, your castle expands which was all kinds of awesome and original at the time. Large scale battles where, if I am remembering correctly, can result in permanent loss of party characters if you werent careful.
The storyline is top notch as well. I read a reviewer describing it as game of thrones meets FF which is pretty acurate. The typical warring kingdom tropes but done very well. I remember getting hit in the feels quite a few times. One of my favorite things about the story was that it didn't drag out. For me Most RPG's have a way of feeling dragged out and eventually feel like a chore, but Suikoden ended right when it should have clocking in at about 40 hrs for me. Keep in mind that was my best time way back in the psx era after having beat the game a few times and missing a few of the 108 characters.
It's been so long since I played the original and it still stands out as one of the all time best RPGs I ever played. It ranks among Xenogears and Chrono Trigger IMO and by all accounts Suikoden 2 is considered better in everyway. I am looking foward to sitting down and playing through both of them over the course of the week. It's a MUST play for RPG lovers.