When I say SPM, most my friends think I'm talking about southpark mexican (some band). Maybe I'm one of the few, but I feel Super Paper Mario is good game. Yeah, the graphics are simple. Its called "paper" mario, not 4 dimensional hologram mario.
The first couple worlds really warm you up, but it does get to be a bit complex towards the end. In a fun puzzle kind of way. You'll probably even have a couple "a haaa" / "eureka" moments. You owe it to nintendo to give it a chance, and you probably wont regret it.