Been using since about 4.0b6 or so. Very fast, very easy to use, handles lots of tabs open without any problems. Lots of nice features. Good rendering. It’s a solid effort.
Good deal... Yeah I’m pretty impressed with it.
Here is a good test for you. Click on the link to see how fast you are connected. If you have anything else running in the background, then shut it down. Just run your Browser.
http://www.speakeasy.net/speedtest/
Now I was comparing Firefox 4 to Google’s Chrome. Google Chrome just updated their browser right before Firefox. They both look the same. Chrome is a bit faster, but Firefox big advantage is their Ads Block. Love it! I hate Ads and I love how Firefox Ads Block keeps your web experience from pop up add. For instance, when you are on Youtube.
At any rate Chrome is a better back up than Internet Explorer IMHO.