I was a big fan of OPERA but encountered problems with the latest upgrade (was no longer compatible with my old operating system) - imported the bookmarks to Firefox without a problem. Firefox starts faster because OPERA had e-mail, newsgroup, and chat clients that I never used. The browser itself is slower than OPERA. The only thing I missed was navigating with mouse gestures, but the add-on for Firefox works now.
BTW - no browser, especially not IE, displays the web pages exactly as designed - Microsoft stubbornly ignores some standards for their browser.