A bit of background first. Reckoning is a 5-point talent in the Protection tree:
Requires 20 points in Protection
Gives you a 20/40/60/80/100% chance to gain an extra attack after being the victim of a critical strike.
This talent seems like a tanking talent, or one that works when you are trading blows with an enemy. You're in melee, you get critted and you wack the mob back with your free attack. Except that's not quite how it works. You don't actually get a free attack. Instead, the time to your next weapon swing is shortened to zero. Sometimes, if you've just swung your weapon, this is close to a free attack. Other times, if you're about to swing, it's essentially nothing.
If you are not attacking someone when you get critted, the free attack happens when you attack for the first time. And for some reason, this will stack. Two crits gives you two free attacks. Three crits, three attacks, and so on. It used to be that you could store an arbitrary number of attacks. Then a paladin soloed Lord Kazzak. Within 48 hours, Reckoning was hotfixed to only store 4 charges.
Note that there is no actual UI support to determine how many Reckoning charges you have. It's completely hidden. However, delaying the attack is important, because the talent shouldn't punish the paladin for being in the middle of a heal when she gets critted.
So the actual way that Reckoning is used is that the paladin will stand around healing herself and hope people attacking her crit. After she stores 4 charges, she targets someone, usually a cloth-wearer, and unleashes 4 simultaneous attacks. This burst damage is often enough to kill someone (or at least heavily damage them).
I think it's pretty clear that people are not using Reckoning as the developers envisioned it. The lack of UI support, the talent not mentioning the charge cap, and the fact that the original version allowed for infinite attacks, all point to this conclusion. I think that it was unintended behaviour--a bug, in fact--that the developers decided was not worth the cost of fixing. And yet this bug is one of the best strategies for actually killing someone in PvP!
To me, this just seems wrong, and is somewhat emblematic of the entire development attitude towards the paladin. Reckoning, as it is meant to be used, is flawed. It does not give you the extra attack it promises! It's only because the talent is bugged, and the bug exploited, that Reckoning is in anyway useful.
I think the developers need to fix Reckoning, even if it upsets all the Reckoning-bomb paladins. Reckoning should give ONE actual instant extra attack. If this fix makes paladins even weaker in PvP, then new abilities should be added, or old ones enhanced. The paladin class shouldn't have to rely on a bugged implementation of an ability to deal damage in PvP.