Combine the style of 3D Land with the multiplayer of New Super Mario Bros. and then dream for the exploration of Galaxy.
http://www.nintendoworldreport.com/blog/34825
From what I've seen and played of Super Mario 3D World, it seems to combine a lot of what I loved about recent Mario games. It has the revelatory multiplayer experience that goes between cooperation and playful competition with ease. Unlike New Super Mario Bros. U, which lost a bit of the novelty factor since New Super Mario Bros. Wii did that multiplayer three years prior, it feels fresh. Each character controls differently and playing together in 3D space is, no shock, a ton of fun. Even the bubble system is a lot friendlier, letting players automatically bubble up when they're left off screen (or some jerk runs quickly ahead while you try to explore).
3D World also has the marvel of Super Mario 3D Land, which is easily in the same league as Super Mario 64 and Galaxy for me. It has that same freedom of 3D space while still retaining some more of the 2D Mario elements that were a little lost in the transition to 3D. The cat suit adds a sense of variety, especially since the suit has so many options. You can climb up walls. You can do a diving strike similar to the flying kick in TMNT arcade games. You can scratch enemies. You can look freaking adorable as a cat with a cute tail and a sweet headpiece. Hell, Luigi is like a spotted leopard. It is incredible.
The one thing that 3D World lacks, at least in demo form, that I miss about older 3D Mario titles is the sense of exploration. It’s what made Super Mario 64 and Galaxy such sublime experiences. Worlds had personality and were filled with colorful themes and characters. As much as I love 3D Land, the landscapes were a little sterile, and at first glance, 3D World might be more of the same. Of course, it might have that exploration, but at this stage, all we can do is guess.
Still, the wait until December will be unbearable. I can’t wait for Super Mario 3D World. Have you seen how cute the cat suit is? It is so cute!