How Does the Feat 'Deadeye Shot' Work?

[Tekill]

Im full of questions suddenly...

So the feat Deadeye Shot. How does it work. Is it any good?

Feat description:

By firing just as your ally connects with a blow, you take advantage of the distraction to strike the same enemy when his guard is ruined. If you ready a ranged attack to occur when an ally strikes a particular target, and your ally succeeds, that target loses his Dexterity bonus to AC against your attack.

Gameplay Notes
Works very well in team fights with a tank.

Does an enemy lose its dex bonus when I shoot at it when it is being attacked/hit by another at the same time?

Does it lose its DEX for just my attacks or does it act like a debuff- flattfooting them?
Do other attackers get the same bonus?

Is there a duration?
Is it for just one attack per round, or for as long as that other person is also attacking/hitting the enemy.

Is it something I activate, like expose weakness?
Or a passive ability?
Or something I toggle?
Or a type of attack that has a cooldown or number of uses?

[Tekill]

Either it is a crappy feat that nobody uses and therefor nobody knows about or it is an uber feat that people are keeping as their little best kept secret.

Or maybe you simply have no inclination to offer me any of your finely honed wisdom and/or vast universe like quantity of knowledge on the matter. At which point I say upon thee: You sir/madam/they-thems, are a big jerk!

Regardless, it does not seem I will be getting an answer to this post. So to prevent a waste of space I would like to invite you all to watch the first episode of the Dungeons & Dragons Animated Series. ENJOY!