It doesn't work!
Just tried it this morning. Download the app and run it on my iPhone4. Tried to make a video call to my desktop PC messenger client (latestest version). The app took a long time and appeared to be unresponsive, and almost wanna kill it. Finally it managed to show me the video call screen and started dialling after seemed like ages. Guess what. No video showing on the desktop client. It's only via WiFi! Absolutely time waster piece of junk!