Karazhan

Our GuildMaster posted the following as the minimum class stats for a Warlock in Kara:

HP: 7,000
Mana: 6,000
Spell Damage: 600 +
Crit: 20 %
Spell Hit: 90+

Depending on your spec, the Crit and Spell Hit may actually end up being lower for the following reasons:

Affliction specced locks don't really need 90+ spell hit as Suppression in the Affliction talent tree effectively takes care of this requirement.

Affliction specced locks don't really need 20% Crit, as Damage over Time spells don't crit.

If, as I am, you are geared into a certain spec, please do not re-spec unless you have the gear to support your new spec.

As an example:

I am Affliction specced, so my gear has very very little +crit. If I go re-spec to Destruction today, my overall DPS is going to suffer, and in turn the raid's DPS is going to suffer, because I don't have the gear to support a Destruction build.

A word about Demonology -

Demonology is a great spec for levelling and soloing, but in my opinion, really has no place in raids. More often than not, you will be asked to bring up your Imp, set him to passive, and use him for the buff. Since the fully specced Demonologist relies heavily on the Felguard for additional DPS, this is essentially a useless spec for raiding. Should you decide to spec Demonology anyways, please do us all a favor and take Improved Imp, as the additional health provided in the Blood Pact buff is helpful.