From that sixthaxis review:
Whats Bad:
Battle music that grates on you.
It makes me wish that this and other RPGs had 5 or more battle music that plays randomly whenever you go on battle so the music doesn't quickly become repetitive.
Hm, there seems to be pacing problems according to Nintendo World Report, specifically those Toad rescue missions. I don't think Nintendo World Review should even factor story as a big minus point since Mario isn't aiming for a great story in the first place.
Meanwhile, gamesradar said that the pacing is excellent. Maybe it boils to personal preference? God is a Geek also said the pacing is spot on.
The amiibo function doesn't seem to be very well-received probably because it's a dispensable mechanic and the methods to use them is drawn out.
The nintendolife one also complains about the similar environments as this: "The rolling green hills, sandy deserts, spooky forest and icy mountain that make up the majority of the game feel slightly tired before you even arrive[...]" I have to agree, unfortunately, we're all pretty tired of these.
Overall, it seems that the reviewers really liked this game. It's probably going to do better than Sticker Star. While Nintendolife said one thing about Kammy Koopa, all reviews didn't really complain about the lack of OCs; some mentioned the lacking story, but expecting an engaging story from any Mario game, including its previous ones, is expecting too much.