I don't think FaceTime (on iPhone 4) is going to work very well in Malaysia here, on a slow internet network. Not everyone need or like FaceTime, for those who need video call, you already using Skype.
So what so greet about FaceTime? Zero configuration. The FaceTime only work over WiFi now, to activate FaceTime, first you need to call through the mobile network. Once FaceTime has been activated through booth parties, you can direct call through FaceTime without initiate with the mobile network.
With FaceTime, Apple will have their own virtual mobile network, over WiFi (or WiMax, LTE). Imagine if LTE (4G network) was included in iPhone 5, and LTE is available near you, you can make calls to your friend without going through the local mobile network.
Check the youtube video, how FaceTime works.