Avast 6's interface is virtually identical to the previous version's. Perhaps the most major change, aside from a slight lightening of the gray in the color scheme, is the removal of the Windows Explorer-style forward and backward buttons. We actually liked those, since they made it easy to return to a previous pane, no matter how deeply into the settings you had explored.
The only other change is the addition of the Additional Protection tab to the left nav area, which hosts the new AutoSandbox and WebRep feature controls.
As mentioned, the two big new features in the free version of Avast 6 are the AutoSandbox and the WebRep add-on. The debut of the AutoSandbox makes Avast the second antivirus option to offer a sandboxing tool for free. Competitor Comodo introduced a sandboxing tool in January 2010. Avast's sandbox probably works differently, as Comodo has a pending patent on its version. And certainly, one of the most frustrating things about sandboxing technology is that there are some indications that it doesn't work perfectly.
installing Avast doesn't require a reboot, and using its uninstall tool we detected no remnants in the Registry or on the desktop. Avast has said that the installer has shrunk for all three versions by about 20 percent, although it's still a large download at around 57MB for the free version.