Nintendo is listing this as an action-adventure game so it is more inline like the previous 3 games. With that being said I do feel like this game will be at least solid and the battle system does seem interesting from just judging from the trailer. Hopefully, this is similar to Super Paper Mario where while not an RPG but the put a focus on the story. The only game in the series I never played was Color Splash, I heard it was solid/average at best.
The thing that is annoying about some Paper Mario fans is that they are quick to call it trash becomes it is not an RPG. With that being said I'm interested in seeing the next Mario & Luigi game since Nintendo has said in the past that is the series that will be RPG focused. Although the games have gotten worse since Bowser's Inside Story.