I feel like the voice actors were talented. I can quote more than a line or two from their characters lol.
Show also pioneered Luigi being a coward and Mario being the brave one. Gave them fitting personalities despite those cheesy voices. I kind of liked the pasta jokes too.
I'm also a fan of the weird scenarios they made up rather than having everything just be directly lifted from the games. Like, episodes where they're all bikers and pasta is a strategic resource. And them interacting with the "Real World" was typically pretty interesting.