I just downloaded Opera for Fedora, and I have a few observations.
1. Yes it is smaller. But in order to view source, you have to set up an external editor. So it doesn't have a source viewer in it. So that was weird.
2. Found a bug already. If you go to
http://www.soest.hawaii.edu/ with both Opera and Firefox, you will see the problem. They have a JavaScript designed to deal with Mac IE. Firefox responds correctly by ignoring it. Opera just prints the script at the top of the page, above the content. Also, it doesn't run the menu function properly - the menu mouseovers are not cleared when the mouse moves on, making the whole page unreadable.
3. The transfers tab is kinda nice. So are all the extra preferences.
4. It isn't open source, and it costs money.
5. It uses Qt, which I don't like.
6. The web developer toolbar extension, which I have grown to love and depend on, is not there.
7. How convenient that it just borrows all the plugins (Java, Flash) from Firefox/Mozilla, instead of having its own! That's sorta cheating, really.
Overall, I don't think there is any reason for me to use Opera. But at least I tried it before deciding.