After having a major disaster with Trijicon HD Nights sights, I was reluctant but ponied up the money for the Novaks.  These sights are awesome!!  

They went on in about a tenth of the time it took me to get the Trijicon HD's on.  There was very little sanding and filing the dovetails or the sight base.  Front and rear sights went on with ease and I was able to center both relatively easily.  

I got to the range and the sights shot just about dead on at 10 years and about 1.5" low at 20 yards which was more than acceptable.  I have to adjust for windage about 0.020" to the left that's it.  

These sights may not be as fast to acquire as lets say a set of Warrens or Heinie Straight Eights, but the sight picture is awesome and I really like the rear Novak sight better than the Warren sights on my G-17.  The Novak Nights sights are dimensionally the same size as the factory sights, however the front blade has a greater height and is slightly wider.  The rear sight is very low profile and less pyramid shaped than the stock sights.