I just tried Opera 8 out and I have to say I am extremely impressed with this browser. Without a doubt it's the fastest browser. I ran some comparitive tests loading and reloading the same pages vs. Firefox and Avant and Opera won. Using the forward and back buttons on Opera as well was a lot faster than the other browsers.
Aside from a few minor things on how it displays objects on the page it works VERY well. They've tightened up the UI. It looks very FireFoxish. The thing I like most about this is that it comes packaged with a LOT of the functionality you would have to search for and install manually with firefox. Such as dragable tabs, mouse gestures, the bookmarks auto sort corretly and can be imported from just about any other browser, even Konquerer. It also has an autoreload, an email client if you should chose to use it, and voice recognition. I haven't tested the voice recognition yet but it sounds very interesting.