First of all, I would like to thank all team members who've been improving opera for all this years. I’ve been using it more than 10 years and I like it very much!
In the age of wide screens it’s very important to use free space with the best efficiency.
The thing I want you to think about is ability to move tab bar to left or right side of the screen (it was available until 12 opera version). It would be very convenient because we usually don’t use all width of the screen. Tab bar placed in the top side of the screen steals useful space. And it could be an advantage over another browsers (e.g. chrome and spartan don't have this feature).
Here is the youtube video to show it - https://youtu.be/Id9Tlip3t9Y.