I personally enjoy the art style for Zelda U. I don't mind realistic graphics but it really is annoying to see fans time and time again that they dislike the game because it isn't realistic. Last time I checked, Zelda wasn't about being realistic but rather immersion. It also is very weird to hear fans say that you can only have dark, gritty themes with realistic art styles. Look at Majora's Mask, a game that is unrealistic in terms of graphics yet is arguably the darkest Zelda game to this date because of the atmosphere, the emotions within the game, and the theme surrounding it. Who's to say that just because we got vivid and beautiful colors in Zelda U, means the game won't be dark? Who knows, this game could take place in a war, maybe Link's friends and loved ones get killed in some way, and of course a psychological plot could be implemented in Zelda U. Only time will tell.
Overall I enjoy the new art style for Zelda U and I do hope we get to see more on a later date. I really want to see Link in his famous green tunic and hat. That would be great to see!