I think night sights are great, but I agree with some posters that they may or may not help depending on the conditions. Billy Dale suggested that if you can see the BG, you can probably see your sights. This is probably true, unless you are in the shadows, then you can't see your sights. To shoot at night, you need to know exactly where your sights are to aim the gun (night sights can help). Point shooting is fine if you really are that good, but I for one am not for any distance over 5 yards. Also, you need to see what you are shooting at. Hence the need also for a flashlight or other light source. I have both for that reason.
The way I see it, chances are that night sights are not going to be a factor if I end of in a defensive situation. The situation is probably going to be point-blank distance and while it may be at night, there will probably be street lights and what not. Then again, chances are I will never be in a gun fight, period. Should I need them, however, the night sights are there and they will offer a decreased time to line up my sights in the dark over not having night sights. The way I see it, that little bit of time may be what saves my life.
Oh, and I definitely can find my gun in the night, next to my bed, in a drawer, etc. without ever turning on any lights. I do like that as well.