I'd disagree with their methodology. So, every Windows Mobile user who has downloaded Opera Mini to try it is considered an active Opera Mini user? Hogwash! Opera Mini has been downloaded 21M times which includes a substantial proportion of people who have downloaded it multiple times and users who have downloaded it to try it and never use it again.
I concur, as a Windows Mobile user (Blackjack II) I downloaded Opera to 'try' and use it occasionally on websites which I know render correctly/better than mobile IE. However much of the web is not Opera Mini compat, and it tends to freeze/screw up quite frequently which forces me back into the mobile IE ghetto.
However it's worth noting that I just installed Skyfire is it's working beautifully.
Shows web pages like a desktop browser (no one-column BS), has Opera/Safari-esque zooming features and plays web video (YouTube/ESPN) with no fuss. Lovin' it.
Technically, not really. Most people I know have the IE of phones: just some crappy Nokia or something that just text messages and phone calls.