The first thing I need to say is that apparently, there are some differences between the Windows version and the Linux version of this beta. The changes aren't major, and most of the changes are customizable, which is a good thing.
As soon as I started Firefox 4 for the first time, I was shown a video about Firefox Sync which I'm seeing for the first time. It's something like cloud computing, but here, instead of the data in your computer, you can carry around the data in your browser and use it on any computer in the world using Firefox Sync. So all your bookmarks, history and saved passwords can come along with you wherever you go. You need to create a Sync account for this first. Since I'm not going anywhere now I haven't tested it out yet
The next new feature is that the bookmarks toolbar has been condensed to a tiny button beside the address bar, allowing a drop-down menu to show all the toolbar bookmarks. There's an option to show the entire toolbar and I chose that right away!
Another change I noticed was that there's an option to put the "tabs on top" of the page. This reminds you of Chrome and I think it's a useful feature, though some might disagree. In Windows I think this appears automatically, but in Linux I had to go to the view menu and change this setting. One change which is present only in the windows version is that the menu is one big button now instead of the whole toolbar (not available in Linux)
The next change is graphical. While a page is loading, its favicon shows a loading graphic, somewhat like a pie chart, and after the page has loaded the website's favicon is displayed. Not a huge thing but it looks neat!
Since this is a beta version, Mozilla obviously wants feedback from users! For this they've included a drop-down box at the right of the address bar where users can report what they like and what they don't like. Apart from this I got a pop-up survey, or "test" which doesn't open in a tab but a small window without disturbing the user's work. You can either close off the window or fill out the survey; its useful to do the latter since it's to improve the software.
In terms of speed I didn't notice anything great - as fast as ever - but then I'm nobody to test technical aspects; this is just a review of what I've noticed from using it so far. The only downside of this so far is that most of my favourite add-ons, including themes do not work














