When I am not connected to Internet connection and someone tries to contact me using FaceTime, I Don't see a missed call notification. This is a big problem as you don't know who tried to contact you. It does show notification when you are connected to the Internet and don't answer the call.
iOS 8.1.2 iPhone 5s
rMBP OS 10.10.1
iOS 8.1.2 iPhone 5s
rMBP OS 10.10.1