I haven't played very much but the barbarian seems pretty weak. In other games it is normally my favourite class but in the beta it dies fast and doesn't do much damage.
It might need more base endurance and perhaps some abilities to counter squishiness. Perhaps a passive/once per encounter that allows the bararian to keep on ifghting below 0 endurance, but takes double hp damage?
As for damage, the issue to me seems to be accuracy. It is way too important in general, and it seems that the barbarian has really low accuracy. Whats the point in having 18+ might with a heavy hitting two handed weapon if you"re almost always grazing, when a rogue or fighter with high accuracy is critting? Accuracy and grazes/hits/crits need to be given less importance so that a mighty heavy hitter is also viable.