Which might not be that good a reference, since I find SMB insanely hard (but I'm all thumbs when it comes to reflex games and platformers, so I might not be a good reference myself)

But yeah, "trails" is not too hard, apart from a couple boss battles. I finished the game, and didn't feel the need to grind (I explored the dungeons and killed most of what came in my way, sure, but I didn't wander aimelessly to trigger encounters like I would have in many JRPG like Final Fantasy, especially with multiple characters to level.