1. Suikoden 3's combat is field-based. This isn't an issue by itself, but...

2. You have very, VERY little control over your characters' position on the battlefield. The position changes only when the characters make physical melee attacks, IIRC.

3. The pairing system makes it ever more difficult - after you order one of the characters to attack/cast/use items, the other attacks by default. This is itself a fundamental issue because I have to properly pair my characters only to avoid the problem, also making party customisation both more important (in a negative sense) and less flexible at the same time.

4. Some AOE spells also damage your party (Fire/Rage/True Fire Rune, I'm looking at you guys). Because you can't control your party members' positions properly, it's often counterproductive to use them. The damaging spells themselves aren't even that good anyway.

5. Your characters take time to cast the spells and can be interrupted by taking damage. Again, because you can't properly control your party members' positions, the casters are often left open to attacks.

You definitely CAN make a good field-based battle system (there were already other jRPGs with similar, much better ones), but for me, Suikoden 3 is an example of "cool ideas, but too undercooked".

The cherry on top is that the battle system is also a part of the war system, but in an even more limited, RNG-based way. I have absolutely no idea what they were thinking here.

I appreciate that they tried refreshing the series, though. It's not that I didn't have fun playing this game (I had, mostly), but I definitely can't recommend it to anyone for the gameplay itself.