Mozilla's Paul Rouget, in a blog post said that Internet Explorer 9 isn't a "truly modern" browser.
"IE9 is definitely better than IE8 and a step in the right direction, but I don't believe it to be a truly modern browser, and let me tell you why."
Rouget takes issue with IE9′s implementation of HTML5, saying Microsoft new's browser (which I've used here and there since it went beta, and it's fine for casual browsing, although, incidentally, I'm sill a Firefox user at heart) actually doesn't support 99 percent of the HTML5 spec. Expanding that further, Rouget illustrates that IE9 supports a whopping 61 percent of Web standards. Compare that to Firefox's 87 percent.
Here's a infographic comparing IE9 and Firefox 4 🙂
[tags]firefox 4,in9,internet explorer 9[/tags]