I first bought just the santoku knive and absolutely fell in love with it, so I decided to buy the full set, figuring an extra santoku knife certainly couldn't hurt considering how useful it is.
First, if you are a fan of Japanese knives like Shun, these give you an equally handsome and *far, far less* expensive option. I am not saying the blades have the same beauty and quality of Shun Damascus steel, but they are sharp, keep their edges well, and are easily sharpened. More importantly, they work very well, so well that I have stopped using my other knives.
This set would also make an excellent graduation or wedding present. And the Ginsu name also gives a fun, kitsch quality.