Warlock it's playable on Endgame. I TRed into this new class my Main with 87 PLs and soloed EE TOEE with it. I played a Warlock 20 with Tainted Scholar Core6/Tier5 enlighten spirit: my aim was to build around ranged damage and a little of CC. Shiradi was main Destiny cause for the nature of the blast it was the optimal choice to further improve damage even If blast has only one projectile.
AOE wise i was very good. Using soundburst from EA and nuking down Hellball+Eldritch Ball and EldritchBlast made most of my trash encounters. Sporadic nukes are OK they quickly get rid of trash mobs.
Warlock it's WEAK single target wise. My biggest concern is that he does 84 animations of blast per minute in auto attack, this means that to substitute Blasting with a normal spells results in DPS increase only If this spell does more than 1.5 times the damage of the normal blast. This situation roughly happens only with Ruin I think. Each time I tried to burst and ball between blasts on TOEE bosses my DPS went down.
Overall I think Warlock performs more than a Sorcerer and more or less like Wiz Shiradi casters. It's not extraordinary like Paladins/Barbarians/Rogues/Bards but I think this gap is due to the nature of the Warlock weapon which is after all a SPELL.