New Super Mario Bros 2 doesn't play at all fast and loose with the established conventions of its predecessors, so it's instantly familiar and comforting.

Your best Coin Rush efforts can be sent as challenges to people you meet via Street Pass. The game can be played co-operatively by two people (bringing Luigi into play), and you soon open a mode called Coin Rush, which involves racing through sets of three stages, under quite harsh time-restraints, collecting as many coins as possible without losing a life.