I disagree.
While I do think Super Mario 3D World is a great, well-polished game, it just is not fun. My favorite part of 3D Mario games is exploring the worlds and finding new enemies/hidden secrets. 3D World has little to no new characters and what is new isn't creative. There's basically no secrets at all unless you count the green stars, which I don't because those are just glorified coins or whatever from the New Super Mario Bros. series.
I played Super Mario Galaxy 2 a week or two ago and I had fun just running around, taking in everything that's new. Enemies, secret paths, worlds, it was amazing. Super Mario 3D World is just 3D Land (which was just a 3D NSMB game, not as bad as 3D World but still annoying) in HD.
I respect your opinion and get where you're coming from. I've played 4 player multiplayer with my family and that is fun, however that shouldn't be the only way to have fun playing a $60 title that Nintendo expects you to buy a Wii U for. When 3D World was first announced I was so excited because I thought they would finally introduce online multiplayer, but nope. It's just local.
Man Nintendo is annoying sometimes.