This pdf is 5 pages long, 1page front cover, 1 page SRD, leaving 3 pages of content, so let's check out the new tools for the gunslinger!
We get a total of 18 new grit-feats, so what exactly are we looking at? There is for example a feat that allows you to aim at an opponent in line of sight, provoking an AoO - if you succeed, you gain your wis-bonus to damage against that creature - until you aim at another or have no grit left.
To represent the gunslinger with the big lip, you may take biting retort to counter an enemy trying to intimidate you by intimidating him instead and perhaps even keep the nerves of your allies calm. If you're crited, you can transform a bit of the damage depending on your grit-reserves to non-lethal damage, take another feat to treat grit as temporary HP and there's also a feat that enables you to last longer, refusing to die due to grit and even come back from the brink of death. Mechanically, you could use grit to soak some damage, add your grit to the negative damage threshold etc. - neat, though Last Man Standing, which enables you to soak damage via grit, needs a clarification on how exactly it works - as worded, it remains a bit ambiguous. While Daron has already commented on its intended purpose and how it works on Paizo's product discussion boards, I'd enjoy an update in the pdf as well.
Think Twice forces your enemies to reconsider whether it's wise to mess with you - while Think Again potentially doubles your threat range against opponents you've warned like that. Riding into the sunset and maintaining good impressions is also part of the staple, as is the power to enter a stance, that, while it makes you easier to hit, adds your nimble moves bonus to damage. Shooting concealed weapons, gaining grit from being downed by superior foes and come back at them with a vengeance and making the battlefield a cacophony of multiple, disorienting shots are also part of the offering, as are 3 deed-feats, which work somewhat akin to deeds:
By spending grit, you may halt opponents in their tracks, deafen them when in a space that potentially has the option to echo or draw your weapon as an immediate action.
Furthermore, all PCs who want to truly go cowboy can now do so with a nice feats that ensures continued power-progression for your animal companion gained via other classes. It should be noted that the pdf also provides a comprehensive list of all the feats herein.
Editing and formatting are top-notch, I didn't notice any glitches. Layout adheres to AA's no-frills, two-column standard and the pdf has no bookmarks, but needs none at this length. I'm not big on feat-books unless they're really well-made and I'm happy to announce that this is an example of the breed: Costing just a single buck, we get 18 feats specifically designed to enhance your gunslinger in not only useful and balanced, but actually extremely iconic ways. The influence of a staple of the best, gritty Western movies and the distinct lonesome ranger/Wild West-flair blowing through the pages of this pdf makes reading about the options for the gunslinger a pure joy that will serve not only to enhance your own experience, but provide some situations at your table that will have both players and GMs smiling at the iconicity of what has just been done. Well balanced, full of flavor and cheap to boot, this pdf clocks in at a solid 4.5 stars, rounded up to 5 stars.