While I'm a Mario fan, I was utterly baffled by the appeal of the four-player co-op play introduced in New Super Mario Bros. Wii.
People tell me: "It's chaotic and fun!" But all I ever experienced was that little jerk Luigi distracting me while I try to make a precision jump. In Super Mario 3D World, however, four player multiplayer manages to avoid the chaos found in New Super Mario Bros. and it's actually preferable to playing alone.
In Super Mario 3D World, momentum is much less important. Momentum counts for a lot in New Super Mario Bros., whether it be jumping over a chasm or dodging an enemy. Having three other players around can affect that momentum, which could lead to a lot of funny but unnecessary deaths.
In general, the action is slower and more measured in Super Mario 3D World than the typical 2D Mario game. There's more on-screen real estate to work with, too, lessening the chance of running into some errant enemy or falling off the screen by mistake. Super Mario 3D Land gives the modern Mario series a much-needed jolt with its tweaks to the game's precision of movement.