Let's be honest, the McAfee of yesteryear wasn't so hot. Intel own McAfee now and whether that has improved the product, I cannot say. What I can note, is that McAfee seems more robust and cures more ills than before.
A seamless and swift internet based installation started it off (on Win 8) and it proved to be fairly quiet, only bothering me when I inserted a USB stick or MP3 player. Even then the scan, as you would expect, was automatic, the information box just a courtesy. It takes up 200mb or so, which may bog down older systems. This has no discernible impact on my PC (or the Mac).
The usual internet security features are there, although less options that with their LiveSafe suite. This dual OS version only offers value if you want to surf safe, protect your online ID and improve parental controls on your Mac, as well as your PC. The standalone PC product is cheaper or offers more licenses.