So, there you have it. In my experience, with or without extensions, Opera has been the most productive, most innovative browser out there for years, YEARS; along with the fastest. Yes, there's all kinds of speed tests that everybody shouts about how their browser is faster. Everyone can make their own decision, so just try Opera on your own PC or Mac or phone or set-top device, with your own favorite sites and decide for yourself.
There's a list a mile long about the useful features in Opera that most of Internet Explorer or Safari users have never heard of, like Speed Dial or Fast Forward. (There's even some, that Firefox users haven't seen, like Rewind and Fast Forward or using your desktop bookmarks on your phone with Opera LINK.) You won't go back after trying it for a few days. (By the way, if you miss how your old browser looks while trying Opera, just go and get a new skin to pretend Opera is IE, or Safari or Firefox. You may even find a cool, new favorite skin that you love, like the Neanderthal skin!)