Spyderco web site should tell you anything you want to know about it's composition.
Anecdotally, I have a Navigator which is GIN-1. I would rate it as an intermediate quality steel, in the same range as 440-C or AUS-8 in terms of usability. Good stain resistance, easy to sharpen, edge holding is between fair and good.
As with any blade steel heat treatment has as much or more to do with performance than the type of steel. GIN-1 that is done well will easily out perform much fancier steels that are less well done, and Spyderco has a reputation for getting it right almost all the time.
Mike