I've just switched from Opera for Android to Opera Mini for Android and I've noticed one interface difference that you guys might want to look into:

If you switch the app layout from classic to phone in Opera for Android and you click on the tabs button, the new tab button (the plus + sign) appears on the top of the layout right next to the tabs button. (In classic mode the new tab buttons appear right next to the tabs button on the bottom).

In Opera Mini for Android the new tabs button (the plus + sign) always appears on the bottom even if you switched the app layout to phone.