First, bring back the fucking menu bar and the status bar by default!.
Go to the Firefox button, Options and check Menu bar. For the status bar, install the status-4-ever extension
I also thought at the beginning that not having the status bar would mean a lack of UI that I will miss very much, but the fact is that I only really need it while I'm hovering a link and in those cases it automatically pops up, so I'm perfectly happy of not having those pixels wasted.
If you look at other comments, people still complain that there's still too much UI in Firefox, and all the browsers have been focused on cleaning up the UI. There's no reason to keep the same metaphors and UI elements than 20 years ago, browsing the internet should be easy and focused on that: browsing the web, not looking at the UI of the browser. I don't mean that the current trends are perfect, but rejecting any changes doesn't help us to move forward; of course sticking to a very old version and then jumping to the latest one will mean lots of changes but staying updated helps to take the changes little by little.
An example of something that I don't like/understand about the current Firefox is that Panorama thing. It could be useful if it could handle all the Firefox windows and tabs, but instead it just allows to group the tabs inside a window and hide the rest so I did test it a little and then forgot about it. The problem might be that someday they fix it and start behaving really well but I will miss it because they introduced it in a broken state and so I no longer have any interest about it