Mine does exactly the same thing and also a few other people have reported it on the MacRumours forums:
Something interesting to note, if you have the 'Camera +' app you will find that the front facing camera operates fine in there. No stuttering, flickering lags, or crashes. Must be an IOS issue?
I just bought my 32gb iPhone 4S black...the moment I opened the camera app and switched it to front face camera and it is just black...I never got an image...I've seen in some blogs that they didn't have any problem with camera+ app but I'm still having a black screen with that app too.
I think it is a hardware issue in my case, because I've already done the reset all settings and nothing happened.
What's your recommendation??? I live in Mexico City.
I'm having trouble with my front camera too, which is anoying after spending so much money (I bought it factory unlocked, 64GB).
To be honest is not much of a problem in my case, but still, I want to be sure that it's a software issue and not a hardware one.
In my case sometimes (very few) the front camera will flicker, or go completely dark (well, almost completely). I definitely think it's a lighting problem, it usually happens while stressing the camera with lighting changes. In every single case the problem gets solved by opening the app again, or even switching from the front camera to the rear one and going back again.
I don't want to exchange it, but if it's hardware, I will. I'm really afraid about getting an iPhone with a bad screen or something like that, specially if it's software and I'm still having the same problem. People don't report this error that much, but, people really don't use the front facing camera that much either, so might be more widespread than it seems...
Well, what do you think? Is it software? Can you check how your camera reacts to these changes?
I've just done a full restore to my iPhone 4S since I thought it could be a software issue...however after the restore and setting up as a new iPhone the problem was still there. I think in my case is definitely a hardware issue. Since I live in Mexico and I bought my iPhone with TELCEL I will go there and have it replaced by a new one.
I hope everyone gets a solution to their problem. I'm afraid of a replacement because now everything is just fine Dow exception of the VGA camera...but I've paid a lot of money for this phone so I demand a full working device!!!