The output in their screenshots look nice, but it looks like there are some cases that aren't handled as cleanly as I suspect LilyPond would render them. In the "Praeludium 10" screenshot on their website, look at the first sixteenth note in bar 21, for example. It's rendered really close to the left margin (and obscures the tempo marking); most printed scores would include a tad more padding for readability. Would be interesting to read their layout algorithm and compare it to Lily's (I guess I can!).