Once upon a time I felt night sights on a pistol were a bit of a novelty. I really did not understand how they worked and in fact was quite naive. There are some out there which are cheap and basically you “charge” with light to get them to glow. Those are called photo luminescent and really should not be considered. When would you ever have time to charge the sights with light before going into a dark area. More likely you would pull the firearm from a dark drawer or concealed holster and then they would not function at all.
The best and only ones you should consider are self luminescent and contain a radioactive isotope of hydrogen called Tritium. The sights actually glow and that light will diminish over time with a useful life of about 12 years since by that time you would have reached the isotopes half-life. I have one pistol with night sights and they are pretty nifty when you can walk around in a dark room and see them glow.
Now the question really becomes do you need them? If I was in law enforcement I would say yes. Typically the LEO knows they are going into a situation and will have the firearm drawn or at least their hand on the pistol and will be prepared to be on target. For the average Joe I think they are nice, but certainly not required. I saw a post on a forum recently where someone said they could not imagine carrying without them. Really? How much time does this person believe they will have from the time they identify the threat to the time they must have the sights on the target? The answer is not long. I suggest if you are going to draw the firearm, you are going to pull the trigger and you probably will be point shooting since the threat will be imminent. There will not be any time to take an isosceles, Weaver or Modified Weaver stance and to bring those sights on target. Now if somehow you find yourself in a dark alley having a gunfight, sure the night sights will be awesome, but that will not happen unless you are already a criminal. The deadly force is not going to be a Hollywood shootout, it will be a random act which happens in an instant and when it is over you are not going to be thinking about how nice the night sights were for the situation.
So night sites are fun, they are great for shooting at night since it has been proven you can get back on target after muzzle flash faster with night sights (fodder for another post), but they certainly are not required.