This is the way my app looked with the "old" app inventor.
This is how it looks with the "new" app inventor test server. The button images look rougher. I use a fix screen size. The size of the images for the buttons is set to automatic. Setting the size to the size of the images, in this case 96 by 96 pixels gives the same effect.
Is there a way of making the effect looks smoother as the where. See here one of the images of the buttons.
Peter