It seems the levels might be short...but then they may just be showing us one size. Perhaps you can choose from 3 sizes or something.
Personally, I would hope we can have
1) an Auto scroll feature for the levels.
2) Descent Vertical control. I think at least 2 full screens for vertical level design would be great.
3) Play as Mario, Toad, Peach, and Luigi...all with their unique attributes.