I just started using it and enjoy it thus far.

The only complaint thus far is that the app doesn't automatically display my book list by most recently read books. It may have that capability, but I haven't figured that out yet.

CoolReader and KOReader reading programs

Basic features of both programs:

- multilingual interface

- reading fb2, epub books

- loading books from libraries via opds

- books by folders

- splitting a book into pages

- customizable text display (fine-tuning styles)

- customizable top status bar

- footnotes at the bottom of the page

- auto-scrolling

- customizable screensaver (book cover, your own pictures) (KOReader - only for devices without ads)

- customizable controls (tap zones, swipes)

- file manager, text editor, terminal, access to the device via wifi

In KOReader, in addition:

- improved pdf support (reflow, zoom, cropping, etc.)

- text recognition in scanned pdf/djvu

- cbz support (comics)

- search in opds

- Favorites collection

- individual style settings for each books

- profiles (reading settings)

- four screen orientations + two columns per page

- night mode (inversion)

- bottom status bar

- comments at the bottom of the page

- pop-up footnotes and comments

- customizable library view (file names / covers / metadata)

- customizable screensaver (reading statistics, your own message with templates, etc.)

- customizable size and position of tap control zones

- multi-swipes

- notes, quotes, export to KoHighlights, saving annotations to pdf

- dictionaries, Wikipedia, Google Translate

- reading statistics

- reading timer

- synchronization of reading on different devices

- full-featured access to the Calibre library

- online services (Dropbox, WebDAV, ftp, news via rss, etc.)

I have it install on kpw4.