The 2-up display totally made my day. I have a zillion art books and now they display correctly!
There are only three features left that I'm looking for now:
- A pretty Bookshelf view

- CBZ/CBR support
- And a weird one but would be totally useful for me: the ability to display a PDF's pages in reverse order, the way comic-book readers have a "manga" mode. I have countless Japanese PDFs of scanned books, and this would allow the correct right-to-left page flow. For a few files I've actually tried making a new PDF with the pages manually reversed (which Goodreader of course displays nicely) but what a pain. A "Right-to-left view" toggle would be much nicer.