I am a bit upset with his focus on Bowser being the main villain. If I may enter some spoiler territories.
You go 5 hours without Bowser being so much as mentioned. The bad guy is Amatsu, the Bat King. The game could have gone perfectly fine without Bowser at all, but right as you're about to have the big fight with cheesy villain Amatsu, Bowser shows up. But instead of fighting cheesy villain Bowser, Amatsu basically goes "Want ultimate power?" to which he says yes, and you fight a super powered Bowser right out of the gate. Bowser is not the big bad, it is a partnership of two big bads, thus doing something mostly new. It's almost the same thing as what happened towards the end of Mario and Luigi: SuperStar Saga, but not exactly.
This game where Bowser is supposedly the main villain remains the only game in the series where you don't just fight Bowser, he's super powered the whole way through.