It doesn't hyphenate correctly. I get the word 'columns' hyphenated like this: 'colu-mns' and 'manuscript' as 'manuscri-pt'. A nice idea, but this implementation is unusable. Justification without correct hyphenation is just a non-starter.
(Edit: bummer. A quick glance through the code at the following link leads me to believe it doesn't actually do hyphenation, though I may be wrong.)
http://ajaxian.com/archives/tex-line-breaking-algorithm-in-j...