It's a lot of fun, and you can probably just jump right into it if you're curious. I didn't play any of the Mario RPGs between Super Mario RPG and Bowser's Inside Story, and if I'm missing things then Nintendo isn't rubbing my face in it. I think all you need to know going in is that Paper Mario is a game that exists.

I guess I should say something to the effect of "not all gaming journalism." I'm a big fan of Gamasutra, but I tend to read their editorials, not their reviews. For instance, this recent piece about how the successful elements of Final Fantasy VII are still relevant is making me particularly happy right now: http://gamasutra.com/view/news/263174/The_afterimage_of_Final_Fantasy_VII.php