So far, the only difference I have seen with the beta is the on-access scanner windows:
No ad (I don't really know if it had been removed before though)
'More options' window has been reshuffled a bit
I like it
EDIT:Helps if I add the images
Man, the gif quality of the Windows snipping tool is crap...
EDIT2:That's better, some nicer images, a bit more work, but it's worth it. And they're smaller
EDIT3:Ok, little thing, not sure if it is the beta or not but:
Open up the skin chooser, and move the window about. Can you see the little bar on the bottom which is completely transparent?
In my image you can sorta see the end of "will microsofts free app..." and Bob3160's name (it was above FF at the time