Ever since Facetime came to the iPod Touch, I have used it routinely with my parents on the other side of an ocean, and it remains the only video solution I've seen that actually WORKS. Skype video and Fring video on the iphone are just horrifyingly bad in comparison, occasionally comically bad, with seconds per frame blobs of color that vaguely resemble heads). Facetime just works, with quality that matches the output when you record an HD video on the device.
All those pronouncements about videochat being something nobody really uses are more or less true.
However, I've heard from some other folks that they use it purely for inter-family communications, where appearances don't matter nearly as much.
There's also the anec-data for me that video chat is just meh. I'm about to jump onto a skype call with an international colleague - do I want him to see me in my t-shirt on the couch? No. Do I want to shave, suit up, and head to me home office? No. So voice call it is for me in a majority of situations - only I believe FaceTime is either video or nothing, with no voice-only option.
Unlike Skype, you have no indication that this person has a facetime compatible phone. Just to get it to call the desktop is problematic because my phone has my phone number as the username and my PC has my email as the username so your never sure where a facetime call is going to end up, and that is if it picks up.