
I'm currently using it. :-)
The reason why I introduce Firefox 3.5 even at the beta version is because it has a lot of improvement over version 3.0.
For instance, speed. You'll get faster loading speed with web application such as Facebook or Gmail.
Note that Firefox 3.5 Beta 4 is the successor of Firefox 3.1 Beta 3 - reason being version 3.5 is to show the significant changes have been made on browser.
It's quite a stable browser so far - which I believe the benchmark results will be published soon, telling how fast it is, comparing with Google Chrome & Apple Safari.
Update: Full download is now available here
If you have Firefox 3.1 beta, just follow the steps below to update:

And note that, by installing this update, the following plugins are not working:
1) Greasemonkey (the engine behind my favorite Facebook Purity)
which i'm sure the updates will be coming soon.
Meanwhile, I'll enjoy this latest Firefox with Adblock Plus...























