I just upgraded from AVAST 4.8 to 7, and the reason I have held out this long (years) is because of two features: 4.8's Enhanced User Interface and the Show Detailed Information option under the advanced settings of the Task (this is the feature that would popup the files being scanned by AVAST in real-time - this is a very useful and revealing tool when you have suspicious activity going on on a system - it let's you know what's going on in the background).
I'm pleased with the current GUI, though I'd like to see more advanced features like these for Power Users and IT Professionals.
Before I switched to AVAST 7 from 4.8 I tried another AV product (Bitdefender). Bitdefender seems to have a good AV engine, but the latest 2013 version GUI looks like it's targeted for the broader audience (dumbed down for simplicity, which is appropriate for most, but I'd like more visibility and control options). AVAST's interface has the most advanced-user features out of the products I've played with lately, so I've upgraded and I'm happy with it (although I'd like to see the Show Detailed Info option from 4.8, and other options like it).
Good job AVAST team.