I put in the Wii U tag, but if my friend's preorder is anything to go by it's definitely hard to get hold of.
As I alluded to in my Horizon writeup, these two games are extremely different. In fact I'm not sure how much more they could differ while still falling into the wide 'third person open world game' category, short of becoming The Crew or something. Horizon emphasises ranged combat with wide selections of craftable arrows and traps while Zelda has you using a wide array of breakable melee weapons. Horizon has experience points and skill trees, Zelda has heart containers and stamina refills only gained by completing side areas. Horizon keeps you pointed in one area while Zelda seems to allow you to walk up to the final boss after clearing the tutorial area (in theory!). Horizon is a showpiece for the most powerful console out there while you can take Zelda outdoors and play it anywhere.
My experience of the first few hours of this is of constant surprises. I don't want to spoil any of them but it has been constantly getting reactions from me. While Horizon reminds me of a low-tech (in terms of weaponry) Far Cry this feels like a fantasy Half Life 2 at times. The world is part of the game system; the map has clearly been designed in conjunction with this. Your weapons may break constantly but you are given a few permanent items for use throughout the game and so far the game's optional shrines have been great for testing my knowledge of them. Using physics to solve puzzles ingame can be a bit of a risk, but so far Zelda has applied its rules consistently and with a sense of verisimilitude (not necessarily realism!) so that it really feels like the game is leading you towards solutions while still retaining the sense of being able to play your own way.
I really feel like I've only just scratched the surface of the game so I won't write much more, but so far this feels like the kind of game that people will spend a lot of time talking about. The way it mixes in high difficulty stuff that I feel like it is technically possible (but improbable) to do has been a good example of this. At one point I was taken by surprise by the console's vibration!