I start using Opera when my PC started becoming slow due to Google Chrome as it consumes a lot RAM. Even it also started crashing and always displays the message "Not Responding" so I started using Opera. Now I have been using it for more than 5 months and even I have set it as my default browser.
It consumes very less RAM as compared to Google Chrome and is very handy. It is automatically updated and every time some new features are added to it which further improves the browsing experience. It takes very less time to open and does not crashes.
At last I would I like to say that try Opera before you use Google Chrome and Firefox.