:( No hyphenation, kerning or leading. Knuth and Liang solved this problem decades ago. I dislike like having to hack it with Javascript. That lack is what makes web typography ugly, even in this demo.
the second was "oh my god, look at those rivers, it's like the freaking Mississippi delta!"
Incidentally, that article in the demo includes Adobe’s own glyph shaping&rendering solution, with things like stem darkening, subpixel rendering, linear blending of text. If you show it side-by-side with the “webkit rendering”, it’s relatively obvious that our text looks better. But guess what…. from all the people who see the demo live (because you can’t see this kind of text improvements on youtube) – nobody notices if we don’t explicitly show side-by-side text comparison. And even then, it’s a “meh, yeah, you’re right, it does look slightly better”.
Same for good justification – it’s computationally expensive. If we put better justification in a demo (we tried), the animation doesn’t look “cool”, it’s slower and the picture lags behind your finger. Maybe it wouldn’t matter in real-life because you don’t need to reflow text 10 times/second… but it makes a huge difference in a demo.
FWIW - my personal opinion is that it was a mistake to shoot the demo video on a mobile phone, the screen space is simply too small to render this kind of layouts. It should've been shown on a Galaxy Tab, it looks much better. (oh, and AFAIK the demo does have hyphenation; it's just that the rendering space is so small, that hyphenation alone cannot solve the layout problems).
In an entirely different context.
You are right that there are real perf concerns. A web page reflows multiple (sometimes hundreds) of times during pageload, unlike a print document.
You can envision some paragraphs of text in a blog post being re-flown but the web is more than that. What about interactive text? Text in SVG? Multi-language text in the same paragraph? Various stacks of text in varying z-indexes, css-3 animated? Text manipulated with Ajax? In a mobile browser AND in the desktop. Not so easy anymore when you have to cover all of those --and possibly in a W3C or HTML5 sanctioned way, compatible with concepts like "overflow" and all.