Opera Mini is an excellent browser for people with limited bandwidth allowance on their phones. I have been using it for perhaps 5 years. Unfortunately for me it has a downside and that is that Opera Mini doesn't display my adsnse units. It is a policy of Opera Inc to strip out what it thinks is unnecessary code from a webpage in order to make the data smaller for the Opera Mini browser.
Peculiar thing is it leaves adverts from many other advertising companies.
2 years ago around 7000 people visiting my website were using Opera Mini, but that has now grown to over 16000 a month. The downside to this increase is that my numbers haven't increased so the opera users have directly replaced visitors that would have seen adverts. With an estimated 1.7 pageviews per visitor I am losing revenue from an extra (16000-7000)*1.7 pageviews each month than 2 years ago. It leads to hundreds of pounds of lost revenue!
My hope is that as mobile operators start to offer more and more bandwidth for less money each month the need for Opera Mini will disappear. At that point I will finally maximise the full potential of my website.