In my experience, Skype is far more well known than FaceTime, it's just that it never occurs to people that Skype exists on their phone. Once you tell them that, a lightbulb goes off in their head and suddenly they're much less interested in FaceTime.

While true, I happen to have both kinds of devices (updated, not old), and we found the Facetime experience MUCH less pixelated and less jumpy than the Skype experience over the same network, back-to-back. In further tests, the Google Hangouts and other Google video offerings were just as pixelated as our Skype calls. Skype is a solution, but here is was case where we could objectively say one approach was better.

On the other hand, I did find that Skype over 3G was conclusively better-sounding than the regular AT&T voice stuff...when it did not lag out with weird chirps.