Before I say anything else, I just want to say, without qualifications, that I had a lot of fun playing this game.
I've previously talked about the first game in this series, but you're not going to be missing masses of plot if you start in with this one. There's a shared world—separated by centuries and what looks to be some continent-reshaping disasters—a similar art style, a handful of inside jokes, and a mythologized retelling of the first game's plot. Literally everything else is different.
The battle system is one of the biggest changes. Rather than throwing your creatures into fights