Anonymous feedback is great because I get really honest responses. I'm consistently surprised at how impassioned the comments are, but that tells me something about my users. Equally I completely respect their choosing to leave feedback anonymously - when I've had a poor experience on a site I don't want to jump through hoops to tell someone about it, I just want to vent - and that's something that FreeRangeFeedback facilitates, but more than that it helps me derive value from their feedback.