WAHA.06X36 The lower-quality scaling is due to using OpenGL and not Cocoa to draw images. It's non-trivial to get higher-quality scaling, but I've got some ideas for that. We'll see.
PDF reading is not easily implemented, as this is strictly a bitmap image viewer, and it would require rendering the PDF to a bitmap and then displaying that, which would waste memory and not work very well, especially not when zooming. Since it would be half-assed, I've decided to leave that up to programs that can do it better for now, unless I have some brilliant idea.
Printing might get implemented later, depending on how much trickery it will take.
(Version 1.2.1)