A question on xperia Z's camera?

There's nothing wrong with the camera. It's pretty much normal for your photos to look like that if you tried to enlarge it. Hope this helped.

Reason for this is because you're trying to stretch a photo's natural dimensions and make it larger. Doing so can cause the photo blur if you go past a certain point. You just simply went past the dimensions, which caused your photo to come out blurry.