I got all the way to the 3rd baddest dude. My reflexes are quite good I think, but I couldn't stay interested in the bland gameplay so I was really just half-assing it at the end.
It says it saves story progress, but um... that doesn't include ANY of the actual fights, apparently. When you die, you start all over from #25. Considering how one-dimensional this game is, I don't see the point in replaying it, outside of bragging rights.
Since you haven't played it, Newbie, I'll sum it up: you stare at a black screen with your cursor in the "HOLSTER" bar. Suddenly, the scene with your foe in it appears, gun raised, and a timer at the bottom. Click on the foe before the timer runs out, or you lose a life. You have 3 lives, and get a refill for getting a certain number of points. I got one at 10,000. You can click on the foe's gun for a Disarm bonus.
For beating 5 stages, view a short scene with the chick in red talking at you, which involves clicking on something. Beat 10 more stages for the second. Beat the game for another scene, perhaps. When you beat 5 stages and no conversation appears, you get to play a Hogan's Alley minigame which I found far easier to get a perfect score on than it is to beat the 15th foe.
That's it.