Which app are you using? My experiences:
1. Tango
Horrible, unusable. Couldn't hear the other person, video was in/out.
2. Skype
They could see me, I couldn't see them.
3. Qik (normal)
Was OK, could hear/see them but if I wasn't on wifi, it wasn't great.
4. Qik (Sprint)
Oddly, this was even better. Still not great (there is no great mobile video chat app), but not bad.
5. Fring
The best I used on wifi/4g, however when a friend tried it on 4g on their side too, it eventually cut out.
So, I'd recommend trying other apps and see if the problem persists.