If you've been using a previous version of Firefox, the fact that Firefox 4's speed is between three and six times faster should be pretty impressive. Thanks in part to the browser's new , in fact, it delivers huge performance enhancements, including faster startup times, graphics rendering and page loads. Firefox 4 also outdid Chrome 10, Opera 11.1 and Internet Explorer 9 in the Kraken benchmark, as I recently .

3. It's a Leader on Privacy

It's no accident that Microsoft just recently Firefox 4's "Do Not Track" mechanism, despite the fact that it had already implemented a like-minded feature of its own. Quietly added to Microsoft's own "Tracking Protection" tool, the addition of the new, Firefox-like "Do Not Track User Preference" feature quickly drew accolades from myriad privacy experts.

4. It's Developed by Users

Who's more likely to develop a product users want--the users themselves, or a relatively limited team of paid developers? Yes, that's right--users tend to have a better idea of what's desirable. And look: Firefox was developed in large part by its users--between 30 percent of 40 percent of its code comes from the community--whereas IE 9 is just Microsoft's best approximation of what users want.