I was looking for a placement for Stanza since that is no longer being developed and has a lot of problems. Ive been using this app intensively for several days now, and this even makes Stanza look like just another app. The best thing about this is that it can download books directly from my PC from my book catalog I use (Calibre, which is free and very powerful) without using iTunes. Since syncing my books individually in iTunes deletes everything on my iPad, Im happy with this solution. Im able to download which of my books I want and leave the rest. Ive downloaded 144 so far without a single problem.
The app has gobs of settings, you can view your books in a list, which is so much easier than looking by book cover when you have a over 120 books installed. You can modify how you view the page with over a dozen different settings, including paragraph indent, line spacing, and hyphenation. There are lots of features for reading including reversing the color to white on black, booksmarks of course, zoom, etc., including a one just for reading Chinese, Japanese, and Korean books.
It supports PDF file and works fine, although there isnt a zoom function. I havent had the need for it yet, as all my books in this format look perfect within the app. It does have the ability to reload the PDF file though I dont know why you would need that. But I have an amazing PDF reader that I use for all my PDF files so if I need to do something elaborate Ill use that.
The only tool it doesnt have is the ability to take notes inside the app. But I can make due without that, just using an external notepad app, because Shubook is just so much better than anything else out there. I highly recommend it.