The only thing I'll tell you, since it isn't outwardly apparent, is that all heroes can now learn any skill (such as Fighters being Wizards). Personally, I still follow the game's rules regarding Shields and such. I could tell you more, but I don't want to spoil the surprise. I was limited in how much I could change, but there is still a lot different. Also, there could be bugs as it's somewhat in beta. I tested as much as I could, but not very thoroughly.
You're also welcome to join the subreddit if you like. I founded it and I host a spreadsheet there that I use for challenge runs of the game. I'll be using the same rules in my full test of the mod.
There's also a cheat list for project64 that you can use to get any item at all, even unavailable things like dispel star Scrolls. The game's full inventory is at our disposal now.