As others have mentioned already, turn based combat in RenPy is pretty cool. This also comes with the added bonus of being interesting to people other than developers because the average VN player is probably aware of the genre's usual limitations due to the ubiquity of the aforementioned engine.
The one suggestion I can offer is that the action buttons could pop up a little bit faster, that would about halve the amount of clicks required to complete a battle. It seems like a minor thing but it adds up over the course of a playthrough.