I have had mine for a few weeks and just posted a review in the main thread, so I will not rehash everything there.
I don't know if it is the single greatest mod ever, but I would say that the improvement to my WOZ was the most dramatic of any mod I have ever purchased for any of my games. So, for dark games, yes, it might be the greatest mod ever.
And to those saying it makes everything too bright or look washed out, it is customizable (through a very easy to use app) from 1 to 100 in terms of brightness for both the general white channel and the infinite number of custom colors you can create in the other channel. Everything being too bright or washed out was a concern of mine before I got it, but you really have complete control of the brightness and color levels and can dial it in to your personal tastes or room conditions.
