Opera has been one of the favorite browser of most of the Mobile phone users before the Smartphones and Google Chrome came into existence.
For Instance, I never used the default browser that came with J2ME powered phones from Sony or Nokia, but downloaded the Java version of Opera browser and installed them in the Mobile Phones. Later then Opera started to make browsers for Computer users, due to its popularity with mobile phones, people started to install and try them in computers too. Firefox, Internet explorer, Safari where other browsers existed at the time. Soon after Google stepped into the Browser business introducing Chrome which is the child of Chromium project, things changed and Chrome started to perform faster than any other browser.
The Rendering engine used by Chromium & Safari is the same ” WebKit ” Engine. Though Safari and Opera are not Open Source, WebKit Engine is a Open Source project which makes it possible to increase the performance of the Browser.
Now Opera is also joining the WebKit community in order to make their browser compatible with all other and to give better performance. Opera has always been supporting Open Source and Open Web Standards along with Firefox & Google.
You can Download Opera from here for Linux or You can install it from the Ubuntu Software Center.