I’ve been looking for something exactly like this for a very long time. Yes, Pleco has an ePub reader, but you have to tap on words you don’t know to get a definition/pinyin. Nothing like this. If you are trying to increase your literacy in Chinese by reading material that YOU CHOOSE rather than uninteresting (IMO) “stories” in similar apps, this is the app for you. If you use it consistently, it will grow along with you like no other app.
Granted, the process of learning raw characters is probably better suited to other methods such as flash cards, writing, and MEMRISE. But this is a perfect compliment to those methods.
I give it 4 stars because the app lacks a certain UI polish. But it does everything as advertised.
REQUEST: for those of us who are intermediate and up, it would be nice to start off assuming all characters are KNOWN and THEN be able to indicate those that are UNKNOWN. Otherwise it takes a loooong time to indicate all the characters/words you already know. iCloud syncing would be great too so I can use seamlessly on my iPhone and iPad.