I find that I'm using FaceTime more and more these days. Having it available over cellular (if you remember, AT&T didn't allow that for the longest time) has made a huge difference... and has made it much more compelling to use. I find that I use it much more on the go than I do while on WiFi. I'm also impressed by the video quality. It's really quite good.
As far as I'm concerned, there are still two pieces missing that could make FaceTime indispensable (for personal and business).
Many times, I have been on a FaceTime call when it would have been hugely beneficial to invite a 3rd person to the call. I'm sure this is a technical limitation (they could add the capability, but it may degrade the quality), but hopefully this is something that Apple is working on.
I find that about 40% of my outbound calls aren't answered. Obviously, I can't expect everyone to drop what they're doing to answer a call coming in, so that number makes logical sense. The problem, however, is that unless they notice the small "missed call" badge, they may actually miss the fact that I called. I would love to see a real visual voicemail system tied to FaceTime... using actual video to leave a message. Again, it may be a technician limitation right now, but I really hope that Apple is working on it.
If you haven't tried FaceTime (and don't have anyone to try it with), head to my contact page and give me a call!