ExtremeTech has a shoot-out of the three browsers, with feature comparisons and tests of resource usage, startup time, and Acid2 standards compliance:

We still think the tab interface in Opera-by far the most mature tab implementation of the bunch-is the easiest to use and understand: At the left of the tabs, there's a "New Tab" mini-tab, with an icon of a page and a plus sign. What could be clearer? In IE7, you don't see that you can add a tab unless you happen to hover the cursor over the small empty tab top to the right of the currently active one; in Firefox 2, you can get a new tab if you know to double-click the space to the right of the last tab, right click the tab and pick New tab from the choices, or actually go up to the File/New tab choice on the main menus. Opera, too, was the fastest to load in our testing and conformed to the standards tested by the Acid2 Browser Test.

Opera alone currently lacks an anti-phishing feature, but we wonder how critical this lacuna is; how about people just learning to be a little circumspect about where they enter their passwords and personal info? If you enter your bank's URL, you're safe, if an email sends you to a site that looks like your bank's, beware. More helpful is Microsoft's anti-malware tool, Defender, which scans your system for spyware you may catch while browsing.

If people switched to Firefox for tabbed browsing windows and extensions, they'll no longer have those reasons to shun Microsoft's slick new browser-as long as they can wait for its release. Microsoft seems to have enough confidence in the stability of Beta 3 to put its download button on the front page of its Internet Explorer site, rather than hidden in some developer area of the site. With IE7 so seemingly fully baked, we have to wonder why Microsoft is waiting for Vista to release it. Oh yeah, I guess they want another reason for you to buy Vista.