This time, it is a brand new, Google Chrome-style ’New Tab’ page. I’m sure it is great for lots of people, but personally, I prefer a blank home page and a blank page when I open a new tab.
To restore the old behaviour, and have a blank new tab, browse to about:config. Accept the warning, then search for newtab. Do not change newtabpage.enabled.
Instead, double-click browser.newtab.url and set it to about:blank.
There, that’s how I prefer it again!
* UPDATE: A slight correction — there is a version of Firefox 10.x called Firefox ESR (Extended Support Release) that is kept up-to-date, so that is also an option!