Completely Open From The Start
The Legend of Zelda: Breath of the Wild will be completely open to the player from the start of the game. There’s very little in the way of progression gating, so you’ll be able to tackle its dungeons in any order you choose (with what I imagine to be some exceptions, for story reasons). This has never really been done in a big 3D Zelda, but was possible in Link to the Past.
This aspect of the game contributes to a general sentiment that Nintendo wanted to hammer into our heads about Breath of the Wild: this is an open-world game, and that means everything you think it means. There are a myriad of environments that all have different nature, weather, structures, and landscapes. It’s a big game, that much was clear after seeing only a small percentage of the game’s map over six hours.