Hyphen is my new favorite ereading app (after having used iBooks, Marvin, MapleRead, Bluefire Reader, Mantano/Bookari, Aldiko, Kybook, Kindle, Nook, etc. in the past).
• Being able to sync not only current page, but also annotations, bookmarks and my entire library of books via iCloud is too awesome for words
• So many fonts to choose from, including light-weight and bold-face fonts
• Easy to customize font-size, line-height, margins, background color, text color, more ...
• Page-curl animations when turning a page!! Yay!
• Adjust brightness with a vertical swipe — you choose whether the adjustment affects just the app or your entire device
• Highlight, make notes, and export your annotations with ease
• Customize what happens when you tap the left and right margins: turn to next page, previous page, or nothing at all — plus you choose how big the tap-zones are
• ADE page numbers!
• Did I mention the syncing thing? So awesome :)
There are a lot of other features, including some I dont use, but will surely appeal to others. And yet, even with all of its many, many features, Hyphen is intuitive, easy to use, and doesnt feel overwhelming to set up.