Is the story less linear this time around? Any meaningful choices? Is the protag at least decent?
I don't think there are any meaningful choices. I'm still in Chapter 1 but it's been just like the last game where the main storyline is a straight path from start to finish, so it seems very linear.
As an example, near the start of the game I encountered a line of dialog that said something like: "We must have missed the person we were looking for. If only we'd came to the Church first to look for them". I was curious so I started a new game and went straight to the Church as quickly as possible and it still had that same line of dialog... so based on that and how the 1st game played, I don't think you're going to find any meaningful choices or branching narrative.
Also, the manual's FAQ says this:
Q: Does this game have different endings or heroine routes?"
A: Nope, it doesn't. You married all these ladies, so you better take proper responsibility and make them equally happy!
As for the protag being "decent", depends what you mean by that. He's still a horndog, but he at least seems to value consent.