Webroot has an amazingly simple user experience, in my opinion. There is literally almost nothing for the end-user to do. The installation is a snap and the default settings are quite good; you don't get popups asking about every single program that wants to access the internet; and it still detects viruses and suspicious activity. It's a pretty quiet program overall with a very small number of false positives, most of those originating from software that isn't malicious by itself, but virus writers often use that software in their viruses.
My mom and I love Webroot, but my dad hates it. Why? Because my dad is a paranoid person who actually prefers to see a huge number of nag pop-ups from the virus scanner / firewall every time a program tries to do anything, whether or not the activity is from a trusted program or a part of Windows. He's somehow adapted his user experience to expect and prefer the constant pop-ups that tremendously hinder his productivity, but that's what he wants, at least in his mind. What does he use? McAfee.