Oh, yeah, I've also been intending to post this - since I tend to recommend Firefox to people over IE (although I honestly recommend any browser over IE, even though IE is making some good improvements), how to make most of Firefox 4 look like previous versions, as I still think that the new UI sucks:
1. Click on the Firefox button. Go to Options, and check Menu Bar.
2. Either right click on the Menu Bar, or go to View | Toolbars, and uncheck Tabs on Top.
3. Either again right click on the Menu Bar, or go to View | Toolbars, and check Add-on Bar. Please note that while you have what seems to be the status bar back, you don't have actual status bar functions back yet, as the Add-on Bar only is a place for extension buttons that is permanently located at the bottom of the screen (where the status bar used to be) if displayed.
4. Right click on a toolbar/Menu Bar, and choose Customize. Drag the Home button back to the left side of the Navigation Toolbar. Also, drag Stop and Reload back from the end of the Awesomebar back to the left side of the Navigation Toolbar. To keep both buttons from combining, Stop must be before Reload.
5. Go to addons.mozilla.org, and install
Status-4-Evar. This will give you back the basic status bar functionality. (Side note: for oddballs like me who run nightlies, and not release builds, if you're attempting to run 4.0 branch nightly builds, since they haven't upped them to 4.01pre from 4.0pre yet, any Status-4-Evar builds past Version 2011.03.21.22 won't work until the Firefox version number is bumped. This is working as designed, per Bluefang, as he has marked it to work with 4.0 and higher, and 4.0pre isn't considered 4.0, even if the current nightlies are the same. Disabling the extension compatibility check doesn't fix this. Oddly enough, this also means that the last build that does work actually isn't supposed to work according to him, but I do know what build I have installed and working in 4.0pre. (shrugs) Release builds will work fine with the latest builds, as does Minefield. Even with this odd issue, I do highly recommend this extension.)
I think that's everything I had to reset when I installed 4.0 branch nightlies over my 3.6 nighly install. If I missed anything, please let me know. At least you can make it a LOT less fugly than IE 9 (seriously, MS, you had to take away the registry hack to move the menu bar back to the top?????). (g)