The pop up blocker is very neat. Probably the smartest and less obtrusive blocker I've used.
I'm unsure about the security panel as I use McAfee which provides its own...so I ended up with a lot of overlap. But otherwise, it too is a great feature.
One thing that annoyed me, and I posted a bug report, was that all my Windows Media Player 9 settings were lost in the update process. That sucked as all the songs I'd removed from the library, but not the hard drive reappeared. Hopefully that's going to be