The reason of the post is not the circular menu itself but the fact that it's entirely made in CSS.
I think this is really impressive.
As a practical matter, you need JavaScript to achieve the best usability, reusability, flexibility, etc. But it should serve as an example to JavaScript widget designers how much you can do in CSS.
It's an interesting and difficult problem designing a JavaScript pie menu component that let you easily and deeply customize it in CSS.
Your typical "CSS3 demo" on HN will work well on Opera, Firefox, Chrome, Safari. It should work on IE10, has a 50/50 chance of working on IE9, and probably won't work on IE8 and below.
Check out http://caniuse.com/ to see which features are supported on each browser.
One other thing to mention is that users might turn off JavaScript support and screenreaders will have issues with some things JavaScript apps do. It was much more of an issue 5-10 years ago than it is today though.