Expertise

New in 2.3 as a replacement for the +Weapon Skill bonus.

What it does is that it reduces the chance for your melee attacks to be dodged or parried. Frankly, it seems like a modified +hit which you could collect in addition to the +hit you are collecting. It also seems to be a good way to increase your damage after you've hit the hit cap.

For ranged attack, since the target can't dodge or parry those anyway, this will be replaced by +hit or +crit rating.

For racials, these are all changed to +1% crit.

Edit: The melee weapon +skill racials are changed to 5 pts of Expertise. Ranged remain as +1% crit.

It's a huge buff to the 'casuals' out there since the hit cap is relatively meaningless since you are never going to meet any lvl 73s, so having +1% crit instead is a direct increase to DPS. For the raiders, it's losing +3% hit on bosses which will have an impact. This 3% will now need to be made up for in gear & gems.

Since Gren is hardly even fighting anything above level 71 (the elementals in Nagrand), more crit is great. :)