So from reading the list of reasons for inaccurate results, it sounds like this library is totally useless for images taken with mobile phones, yet it is only allowed to run on mobile ;)
Now I would be more interested in an image correction library
"....
Blurry images
Handwritten or cursive text
Artistic font styles
Small text size (less than 15 pixels for Western languages, or less than 20 pixels for East Asian languages)
Complex backgrounds
Shadows or glare over text
Perspective distortion
Oversized or dropped capital letters at the beginnings of words
Subscript, superscript, or strikethrough text"
It depends on what is being scanned. Say you have a perfectly formatted image, directly taken from a scanner, it's a pretty darn quick process.
But from my experience, what adds to the slowness is pre-processing the image to make it suitable for OCR, especially tesseract. I still haven't found the magic combination of filters because every image is different, especially if your source them from users camera phones.
http://en.wikipedia.org/wiki/Turducken