The world in The Witcher 3 is biiiig. But, to solely judge it on its size would be to do it a disservice. It's how the world is connected and how everything is put together that makes the world feel even bigger.
The world of The Witcher 3 feels large because everything is connected. It's woven by the main storylines and awesome sidequests, which should set the new standard for future open world games, including Zelda. Novigrad, for example, genuinely feels like a living and breathing city. Characters will reference events that are taking place or have taken place either there or elsewhere. It's one of these things that you just have to appreciate for yourself because, to me, no words that I can say will really do it justice.
The new Zelda has a LOT to live up to. The size isn't the be all and end all. It's what you do within these areas and making the world feel alive...that's why we play games in the first place. Skyward Sword's world building was absolutely pathetic and a huge bummer. There were no pieces that you could put together, no background information or lore that you could become engrossed in. It's as shallow as they come. You can't have a map and see several landmasses and call them "a world". You could get away with that in the past, but everything has changed and evolved now. Now it's about how you interact with characters, or how a simple conversation may result in something happening further down the line, even the death of a character.
With The Witcher 3, I wanted to learn absolutely everything about that world, because the world that they had built was very intricate, dangerous, full of secrets and magic. I couldn't wait to shelve the last Zelda. I'm not even excited about the next one because Nintendo have yet to convince me that they really know how to craft these complex worlds in this modern way. Talk is cheap. I want to see something to get me excited and I hope that they have something at E3 that will do that.