The reason? RSS-feeds. I no longer have to keep hitting refresh on LJs or my friends list to check for updates- I can subcribe to journals/communities for RSS feeds by clicking 'RSS' when visiting that particular journal. Then when the LJ is updates, voila- I get notified.
Its so intuitive, and not buggy at all, which is rather unusual for most new tools in alternative browsers- but that's Opera. It freakin' rocks.
I can even RESPOND through the RSS window- almost like a regular chatting program. Way cool.
*runs off squeeing*