My experiences are different, as last year I ditched it off 2,500+ PCs because it had got so completely bloated that in order to be effective, the load it puts on the PC makes it's almost unusable.
As an example of just one review these people don't even put it in the top ten any more, and I don't blame them.
AntiVirus Software Review 2010 - TopTenREVIEWS
McAfee need to tear it down and build from scratch. All they've done is bolted on more and more add-ons and turned a decent product into a pile of poo.