In spite of things that have gone well with Apple's Safari 3.1 web browser, a large number of users are still reporting problems with the new application. The guys at MacFixIt have posted the following tips as to go back to Safari 3.0.4 should they need to via this article:

Download Pacifist from here and either the Mac OS X 10.4.11 or Mac OS X 10.5.2 combo updater (if you run Tiger or Leopard, respectively) -- available from Apple's download page. After installing Pacifist, drag the appropriate combo package updater onto the Pacifist icon and select /Applications/Safari.app from the list. Use the "Install" button at the top of the Pacifist window to force an installation of Safari. Next, select /System/Library/Frameworks/WebKit.framework and install it in the same manner. Restart your Mac.

From here, run the Disk Utility program (in /Applications/Utilities) to repair permissions which can become damaged after installation of Safari 3.1.

For my own part, Safari 3.1 has handled everything I've thrown at it pretty well, despite some extensions needing to be updated. If you try this fix, let us know how it goes in the comments or forums.