Everytime I try Opera Mini it gives me problems; since I can see a good 95% of what I want to see with the native Blackberry browser, I don't mind overmuch having problems with the remaining 5%. (While it's great fun to use my BB for Internet, for some things it's just easier to use my PC at home.)
i use the native bb browser for most sites. i only use Opera Mini for sites that have a lot of graphics or features that the native bb browser cannot handle, such as teva and orbitz and full ebay.