The overall artstyle is the same, yes. It is clear that they are a ton of small improvements made overall though. The lighting system is even better than it was.
The lighting even covers even the most simple blade of grass. Speaking of the grass, the wildlife, such as birds, and butterflies are now present as well.The sky is much more rich and dynamic. The most noticeable thing is frame rate however. It was very clear that there was some stuttering last year, and that was noticeable.
This makes the animations silky smooth, making up for the inevitable clipping that the game has at certain frames.
Like
@G-King mentioned, I really hope they cleaned up some of the rock textures, and I think they did do it.
Take a look at this. Look at the right side of the picture. It is hard to tell, but it looks like that instead of the rocks being a flat texture like they were last year, they are now involved in the intricate lighting system.
The rocks look a lot better I think.
I think the main focus with Zelda U however, the reason it was delayed, was for content though. I think also we will get a better grasp of the graphics of the game once we see more areas such as Death Mountain, seeing the new Water realms and streams, ect. I think that is where Zelda U will shine the most. We could see some water in the distance from the teaser, it is hard to say, but I think that the water effects may be improved as well. Only time will tell however.
So yeah, I think the game definitely looks better. Even if these are small tweaks, it still looks really good. They showed so little of it that it was hard to get a grasp of the graphics. Yet once you slow it down, you can see a lot more, and I think that it is beautiful.