Much as I rag on DnD Next for various issues and flaws I do like one of the things they are doing in the latest packet - fixing critical hits. In DnD 3rd Ed. critical hits got absolutely absurd with players often doing treble and sometimes quadruple damage. Of course monsters did the same thing when they used weapons so the game ended up chugging along normally until somebody accidentally died. This is best illustrated by the random orc that swung a greataxe for 1d12+3 damage. This orc is meant to be a reasonable challenge for characters with 6 HP even though it is clear a single regular hit could quite easily kill anyone. When the hit instead is for 3d12+9 it gets silly - that is easily enough to one shot level five characters for whom the orcs are supposed to be a trivial challenge. The DnD Next version of critical hits has attacks doing one more die of damage on a critical.
Example: Regular hit - 2d6+4 Critical hit - 3d6+4
This is a sensible way to do criticals. Monsters that hit like trucks don't just blow characters out when they land one of their rare critical hits and you don't end up rolling max damage and doubling it to end encounters or campaigns in a single swing. Heroes By Trade did something similar in that a critical hit ignores the Armour of the target so that the attack does full damage and is not reduced by Armour as normal. In both cases the added damage is noticeable but never runs to extremes; this is important if you as the GM want to avoid fudging dice or cursing when the villain dies ahead of their time.
Both systems have specific weapons that are good at delivering criticals. The approach is wildly different though. Next has weapons that add more damage on a critical but never change what is needed to achieve one - a natural 20. HBT has weapons that increase the critical range from 20 to 18-20 or 16-20 but the effect of the critical remains the same. I kind of like the Next version better in some ways because it keeps weapons feeling very different and unique because their added damage dice are all over the place. I specifically built the HBT weapons the way I did though because I wanted random dorks who are trying to take down The Colossus Of Doom to have a way to attempt that. Even if said Colossus has an absurd Armour value they can use specific weapons to try to score critical hits to defeat it.
It is not a decision where I feel there is a clear right and wrong - having monsters that are effectively unbeatable is an interesting choice. HBT was built to make that not really work because an enormous army of dorks with bows really can beat pretty much anything. I don't mind that overly because I want armies to matter and I value characters having to respect the power of an army too. Critical hit design is part of my way of doing that - even if you are really awesome the dorks will eventually roll 20s, ignore your Armour, and blow you up.