I have had no problems with lighting. Is it only when you're in dark dungeons, etc. or is it too dark all the time? Assuming you have raised the brightness both in game and on your tv, you shouldn't have a problem. I've found that the lightning is perfect on some tvs, but can be completely different on others, so I don't think the problem is actually within the game.
In-game, I have the brightness set as high as it will go. On my TV, it's set to 75 (on a scale of 0-100.) If I set it much higher, the image begins to lose its depth. The issue is not the individual brightness, but the complete range of the brightness. The entire image can go way too far into the darks, and it does it way too often for me to ignore it. I can be in a decently well lit room, have a candle in what would be my character's peripheral vision, turn away from it, and have to deal with 2-3 seconds of almost complete darkness before I can see anything again. I really, really wish it wouldn't do this.
I believe they are attempting to simulate the effect of your eyes having to adjust to the dark, or vice versa.....
Occasionally its annoying, but its a cool effect in certain situations.
I figured this is the case. If so, it's too dramatic and happens far too easily. I don't know about you, but even when I stare directly into a light, and turn away from it, I don't go blind for 2-to-3 seconds. And, honestly, I could see something like this working in, say, a horror game, but it just doesn't have a place here. It's annoying, it's impeding, and I don't find it ambient, interesting, or fun.
EDIT: I would also like to add that, for whatever reason, the issue isn't nearly as prevalent outside as it is inside. I'm guessing it's because of the lack of ambient lighting?