One problem that can happen on occasions is weird full justification of a short sentence. (madgeniusclub.com)
The lack of proper full justification is annoying, and it's disappointing that a technology touted as a replacement for books still can't do books right. (guidohenkel.com)
There's also the option to choose full justification, left justification, and you can turn justification off. (goodereader.com)