Your millage is especially going to vary with older games. Particularly with 16-bit (and god forbid 8-bit) stuff that has the more complex characters very pixilated, the camera feature is going to have a really serious problem reading most of them, and I'd imagine even a problem reading some of the stranger fonts of the more simple characters. I'd imagine you'd probably be fine with most newer games though, at least as far as actually recognizing the characters onscreen is concerned.
Like Bone said, it's going to be very far from perfect even in the best case scenario. For stuff like menus you should probably be alright, but as far as understanding what is going on at any given point, it's probably not going to give you either the clarity or the actual character recognition needed for something like that, unfortunately
I identify everyone via avatar, so if you change your avatar, I genuinely might completely forget who you are. -- Me