not to be a dick but did it really take 20+ hours for you guys? between this and people saying the game was hard, I don't get what is going on. I'm not good at video games and I got 100% everything in under 10 hours (around an hour per world) and didn't think it was hard.
and agreed with prole about the terrible waggle stages. I liked the waggle spin jump that is always there, but waggling to pick things up and tilting things is terrible and unnecessary. Once I had 99 lives, literally the only time it went below were those stages where you tilted platforms. It was only challenging because the game didn't let me play naturally, which apparently involves me holding the controller constantly tilted left.
actually, the game does get significantly harder when playing with friends. At least playing it solo the game is easy and not that long, but two people playing at once makes things harder unless you're both perfectly synchronized. Playing with three others is hilarious and fun but you won't be making any progress.