I was using Opera heavily until about 6-7 years ago when the compatibility just became too bad. The feature I miss most is the keyboard shortcuts (which this seems to have) and 'fast forward'. This was a neat feature for paged sites where the browser would try to parse the site for 'next page' links, preload it and when you hit the fast forward button it would show it immediately. Worked great in all kinds of user forums and photo albums back in the day - although granted, there's much less paged content nowadays. I used to put back, forward and fast forward on the 'z,', 'x' and 'c' keys, sort of similar to vim (although I was never a vim user). It really felt like being in total control of your browser and having the web at your fingertips.