With the current release, Opera for the desktop is now free. The unregistered version has been free for sometime, but displayed an add banner in the top of the screen. The ad did not in any way reduce the size of the main browser window.
I’ve been an paid Opera user since version 6 dot something dot something and have willingly paid to upgrade at version changes (from 6 to 7, from 7 to 8) because I like the browser so much. I was attracted to it because the many of the web designers who frequent alt.html recommended it because it was W3C compliant.
If you would like to check it out, you can find it here.