Thanks for noticing! We improved our full screen experience with our last release. Now it actually takes up the whole screen instead of just the whole browser.
Very interesting that you found that zooming in makes the slide show more pleasing. Did you press "Enter" after going to full screen? By default we keep the image the same size. Pressing Enter makes it take up what we think is the "right" amount of space. Does this look good to you?
How do other people feel about the amount of space the photos take up after you press Enter?