You had me at "full screen mode".
I've been hassling fictionwise to make eReader do that for a while now. It's especially nice for widescreen reading.
I just started using it a few minutes ago, so I don't have a ton of feedback, but I did want to throw a thank you your way. Thanks!
I second a desire for tiled background images. I'd also like to see the ability to sort books into categories, rather than having a single long list. I have a lot of ebooks.