This guy was an elite brute swordmage using something with a boatload of maximized dice. I count myself lucky that it hit my 18 Con fighter with Toughness at full hit points. I went well past bloodied in that one hit, but it would have darn near wrecked me if I'd already taken much damage. Even worse, it would have KO'd pretty much anybody else from full, or killed them from bloodied.
Crits are scary because full hit points are not an adventurer's typical state when most of the dice are being rolled.
-blarg
Henh henh henh.
Now, for the stats:
Level 6 Lizardfolk Blackscale Bruiser, with the Swordmage NPC class added on. The power that did the damage was... Frost Backlash, which let him dish out something like 3d12+3 cold damage in response to an attack. (I say "Something like" because I only have the book nearby, not my notes). And yeah, he got the crit.
Later on, that same night, in an different encounter, the same NPC hit the group's rogue with the same power. She went from nearly full HP to unconscious. Gotta say, I enjoyed that.
***
On to the point at hand. Criticals favour the PCs more these days, and I like that. The game should focus upon the Players, and not try to favour some sort of equilibrium between fictional PCs and fictional NPCs. The PCs are the main characters of the story, and they should do more in a combat.
Why do Crits favour PCs? A few reasons:
1) PCs usually have items (weapons or implements) that will increase damage on a crit.
2) PCs can heal; most monsters are unable to (or, if they can, can really only heal a small amount). Thus, even if they do get a hit, they just have to fight on the defensive for a round or two. This is what happened the first time my lizardfolk Swordmage hit the PCs - he caused the group to collapse and try to keep their heads above water while the other lizard folk set up a flanking maneuver.
3) PCs will do more damage on an attack on average, since they will have more encounter powers and probably more daily powers than a monster. Monsters may do more damage on a basic attack, but PCs rarely do basic attacks. If I had a monster that dished out the damage per round that my group's archer/ranger did using Twin Strike, I'd have a riot on my hands. More damage means higher criticals (obviously).