Disclaimer : I do not have any preference for a perticular browser, these are just observations. Opera has better GUI. Not interms of look and feel, but in terms of usability. Mouse gestures are example.Opera caches lots of things. It is both good and Bad. It increasees "perceptible" speed of browsing since pages appers to load faster. But it puts load on memory. Opera remembers last set of pages that were opened. So if you launch Opera next time, you can start from where you left. Opera does not have DOM inspector. Opera is not Open Source. Opera does NOT have scripting capability. If you want to write a program that:1. Logins to gmail/hotmail or your bank account2. Navigates to a perticular page3. Gets some value out of DOM tree4. Does something with itIts a 10 line program with IE or Firefox, not with Opera. Opera users, point out if I am wrong. I have been using it just for a few months.