Wherever these Nitestiks are sold, the sales blurb always over sells them so that many clients are disappointed.
However I have used one for over three months now, attached to the lanyard of a torch so that I can find it in the dark, and am very happy with it.
Have just bought two more for the same purpose, to add to other torches (January 2012 - two for £10).
All three that I have are the "crystal green" colour which I understand are supposed to give off the best glow, though I can't compare as I have not tried the other colours.
If you expect a bright light then you are going to be very disappointed, if you expect a faint glow that will be sufficient to help you find something in the dark then they are excellent.