Kowloon Gun God incorporates "cinematic" abilities for the type of agile character that uses modern automatics such as Glocks, SIGs or H&Ks. Lots of rounds to use, lots of acrobatic abilities. The KGG offers a prestige path beyond Gunslinger, or quite possibly a complete alternative to the Gunslinger if planned well in advance.
This is a very nice prestige class that adds directly to the d20 Modern opus. It does exactly what it sets out to do: it explains where the inspiration for the class comes from, so that GMs can easily decide whether it fits the campaign culture; it explains the class in the usual way; and lays out a feast of talents. I also liked the background the publishers add to make it more than just a greyscale PDF. If I have one criticism, and it's a small one, I don't love the placing of Bonus Feats, which are tucked away toward the bottom of the class description after all of the Talents. I believe Feats should be placed directly after the Skills section.
I would love to run my character through KGG: in fact I would like to acquire two complete talent trees, they are so mouth-watering! I highly recommend this to players of agile, daring characters that are familiar with modern Autoloaders.