I am coming from a Sony PRS 350 to Nook Color so when I am reading in the dim light, I go to the minimum possible brightness (without making the screen flicker). Anything more looks too shiny. That is one reason I gave up on the Kindle app. It wouldn't get completely dull or paper-like even at the lowest brightness. But FBReader can. However you have to swipe the left side very carefully. Nook app can give me that as well. But with a lot of fiddling. That is why I am loathe to lose that setting during daylight reading.
(Using Adj Brightness app, at 5% brightness setting it can be a comfortable read. At 4% the screen starts to flicker.)