After watching GameXplain's analysis of Mario Maker's gameplay footage in the Game Awards, I can easily say that I'm more excited for this game than Zelda. Especially if it lets you share levels online. There's a whole bunch of customization the video points out and the ability to easily implent them in the game is absolutely amazing.
Here's a few thing they GameXplain noticed:
You can add wings to spiny's, blocks, and maybe even more enemies.
You can adjust an enemy's size
Enemies retain their unique behavior in respective games. (Koopas poppng out of their shell in Mario World but retracting into them in other games)
You can put enemies in ? blocks
You can possibly time events like cannons
Possible power ups from other games (maybe even Yoshi!)
Here's the video link below: (I don't know how to embed)
https://www.youtube.com/watch?v=b0TVMg7Cs3c&feature=youtu.be