I've just completed a playthrough with this mod and I can say that this project is obviously a labor of love and it truly enhances the original game. Unfortunately it's not perfect as it falls into the usual trap of overdoing it with the changes just for the sake of it and not because it necessarily improves something in the game.
Let's start with the positive changes: First of all this is not just a graphics mod as it fixes the notorious land effect and XP bugs of the original game and it adds an auto item passing feature. Most of the new battle sprites for the heroes are amazing, especially the centaurs! Every hero has his/her own unique appearance so there aren't color palette swaps anymore. Most of the bosses have new battle sprites too and they're bada$$! The new map tiles make the villages and towns look better. The new graphics to the title name of each chapter is a nice lil touch.
Now, the negative: The repurposed character portraits from Suikoden 1 for the shop merchants and some unique NPCs cheapen the overall effort... it's too much of a recognizable and popular RPG. IMO, it's better not to use anything than ruin the game's universe. Sorry, but that newly added shellfish monster battle sprite is ugly. It's way too simple a design to fit well with the rest of the game. Also, I prefer Kane's original character portrait. The new one makes him look like a ninja than a knight.
Neutral: There is an obsession to make this game look as close to Shining Force II as possible. Many monsters are recolored versions of the SFII ones. Hero portait backrounds use the SFII style and some battle backgrounds have also been replaced with SFII ones. Don't get me wrong, Shining Force II is my favourite game of the whole franchice and my childhood, but I also like the unique art style of the first Shining Force which is more childish / innocent and has a comic book feel to it. Also, the mod's description doesn't mention anything about it so I don't know if this is a new feature or a bug, but some bosses were regenarating some HP after the end of a whole turn, a mechanic similar to Fire Emblem. It added an extra difficulty factor, I liked.