I've been waiting for something like this for ages, before I'd convert the books to txt files and read them with moonshll2 on a DS flashcart, but my flashcart has taken to crashing and loosing it's connection with the sd card.
A bookmarking feature will make this a must have replacement.
Edi1: Does the app support subfolders under Root/Books ? As that'd be handy for organising your ebooks, or is this a potential feature for a later version?
Edit2: What is the largest filesize can this ebook reader tolerate so I know how to split them with the Caliber conversion.
Edit3: Seems my ebooks are still crashing the app even after using Caliber to convert them...