It's a big disappointment for the developers of Opera. They've made a version of Opera Mini for the iPhone, but it has been blocked by Apple to be sold in the App Store.
Apple didn't give an official explanation for the refusal, but Opera is suspecting that it would probably give too much competition with Apples own browser Safari. Another explanation could be that a version of Opera Mini is going to give Apple a security problem and there is a big chance that Apple is not able to take action against this. Nevertheless, the developers did already make a version for the iPhone, but it seems that they can throw it away.
Safari
People who really like Opera Mini or other browers have to keep on using the buggy Safari browser that is placed on the iPhone as a standard and only browser. The functionality is fine, but the speed is really not that great and can probably be improved a lot.
Source: NY Times