Built in spell checker alone is worth it.
While I do appreciate having a built in spell checker. Most of the words I get wrong are from typing fast and I usually hit submit before I would have even noticed that there was a red line.
Being able to undo window closings, nice.
Having built in tabs and gestures, nice.
Having the fastest renderer, nice.
Being the target of practically zero exploits, nice.
I am pretty sure there are other things I like about Opera. I just take most of them for granted.