Generally a green tint to photos means you have fluorescent lighting impinging on the subject. I have not found any color shift or tint in my indoor photos or outdoor photos for that matter. And using the "flash" hasn't cast any tint either.
I just got the phone yesterday so I havent had much time to play around with the camera yet but check out this link. recombu.com/news/samsung-galaxy-s3-camera-tips-and-tricks_M18048.html It shows how to get to more of the settings. From what I have seen its a very good camera. I have a $1000 nikon dslr that takes terrible pictures indoors if its left on "auto". Most of the time you just need to figure out which settings to use in different lighting conditions to get very good results.
I read a review that said the green tint only appeared on the phone. If you upload or email the pics... they are normal. Not sure if this is the same situation though... email the pic and view it on your computer to check.