As another example of Font-Awesome in production: I've incorporated Font-Awesome very heavily on my own blog, and it works very well: http://minimaxir.com
They look ugly with Chrome + if fonts are not supported they don't show anything. At least if the image is missing you see X.
If you're designing things such that a missing icon causes the UI to be incomprehensible, you're probably designing it badly
The urge to plug your blog resist you must.If there was a way to show off Font Awesome without providing a link to a case where I actually used it, I would. (screenshots won't be as effective since I incorporate on:hover effects.)