I get that its very usable from the designer's point of view. They can just drop a little script like this into their document and forget about it, but after the umpteenth little script like this, won't performance become an issue?
My other issue is that until we get decent rendering across the board, anything with @font-face such as this is just infuriating to read. Whilst my browser of choice (Opera) is one of the more niche ones that people might not care about, a recent thread here on HN mentioned that Chrome on Windows also suffers from the chipped away look with @font-face - meaning a lot more people are exposed to this annoyance.
I think it's appropriate, since it's a rendering issue. In the future, the JS can check whether the browser renders things properly, and just skip the whole process.
(And, yes, I do know about the Readability bookmarklet. I'm just hoping that some day I won't need it.)
It is sad that browsers are not taking typography seriously.