Mozilla has recently released their new update from Firefox 2, to Firefox 3. They are only in the 3rd version of the beta release now, and so far it looks promising, but there are still bugs and glitches that need to be fixed, hopefully they will be gone in the 4th beta, but that's only a hope.
One of the biggest bugs I find is when I watch DivX movies or some flash movies online with Beta 3, the browser starts to fail. Everything goes black and you can't scroll down. it is a large nuisance because if I leave the full screen view, and everything goes black, 1) I can't watch the movie in fullscreen. 2) I can't even see the movie because everything is black!
So far, there are very few of the famous Add-Ons that Firefox users love, for the release. One of the problems is that they don't have a Pop-Up blocker add-on. In Firefox 2, there were third-party and mozilla made pop-up blocker add-ons. These were convient because they run in the background of the program, with a little icon in the bottom corner, that is hardly noticable. This is much more convient then a toolbar (i.e. Google, yahoo). Either they will soon have this add-on, which I find one of the most important ones, or they will just incorporate it into the software itself.
Beta 3 has good secuirty features though. New higher secuirty means that you are more protected from fraudulant websites. Also, the new system that tells you if you are connected to a verified website. This is mostly for if you are using a corporation website, like Microsoft, or Google. It tells the user if the site they are viewing is verified and/or encrypted. This proves helpful when using online transactions with PayPal or a credit card for maximum safety.
All in all, if you really want to try out Firefox 3 Beta 3, go right ahead. But I would wait for a few more releases to come out before investing time into it.