[nikki9696]

The author is premature in such sweeping praise.

"They prove that a buttery-smooth UI is not impossible to build on the web."

In my opinion, this application has not proven such a thing (yet), since it doesn't work in IE. I don't build UIs that don't work in IE.

"It shouldn’t be a magical surprised that a good, no-compromise UX is possible on the web."

And yet, currently it DOES compromise. It doesn't work in what is currently the leading browser.

Don't get me wrong, I hate IE and the iCloud application is nice and slick. But it's not currently a viable UX for the most popular browser in use, and therefore is not a viable UX for many web applications. Yet. I have hope for them, though. It does look promising.