Web page compatibility is fine here. The rise of Chrome and Firefox means that Opera has benefited from the previous IE-only web of yesteryear.
I have no more problems than I do from FF or Chrome.
And clearly it’s not about desktop marketshare.
Opera is the king of mobile (bigger than Android, bigger than iOS).
http://gs.statcounter.com/#mobile_browser-ww-monthly-201202-201205-bar
It’s also VERY profitable.
http://tinyurl.com/OperaSharePrice
If those aren’t measures of success, I don’t know what are… Much better looking than Mozilla’s finances.