Suggestions for future updates
So there is already replay value, and as I go through the game with my first party, I am already excited about my second party.
However, it would be nice if there was more than just 1 advanced class per. For instance a crusader can become a Paladin currently, would be nice if he could also become say a Lord with a different set of abilities. It would also be nice if the choice came with not just 1-2 abilties, but also came with 1-2 extra skill expansions, as in skills that for the base class are only expert or master, but because of your advanced choice are now master or grandmaster. Again using the Crusader the two choices could be: Paladin gives access to two-handed Expert where there was nothing before, while Lord gives access to Shield grandmaster where it's currently master.
Chat functions. I play another single player game that actually has a pretty good community because the game designers added chat channels that could be joined. So although you're playing by yourself, you're not actually by yourself. So one, it provides a means for in game technical support if you choose to go that route, but it also just lets the community help each other. Rather than having to come to the forums where you don't know if you'll get your answer or not. And since you obviously can add the feature to leave all channels, and make it so the game still runs fine without being actively connected, this shouldn't detract from the game at all, just add something.
Spells. There are 1 grandmaster and 2 master spells per tree. This is barely anything. The trees should be expanded in my opinion, players love choices. Also the Dark grandmaster spell is pretty bad compared to the others, not sure if you can do anything about that. Although if bosses aren't immune to it, I guess it is really good against them. But even still, the turns it lasts is so low, even then it still feels like an expert level spell, not grandmaster. If you're having trouble coming up with ideas, and that's what is holding you back, just start a sticky thread asking for player suggestions on spells, I guarantee you'll get more than enough good ideas.