Used to be a lock ages ago, and feeling like playing one again, just wondering how the class is doing? (its been years so I know many changes have occured!)
Personally I love mine, the aggro issues are much less evident when grouping and you can deal some serious dps - especially on encounters.
If you take the time to learn the ins and outs of the class, you can hold your own dps wise with anyone and limit your aggro issues. If you dont however this class doesn't have the easymode 1 button dps of wizards and assassins and our ability to pull aggro is second to none.
1. Wizard 2. Warlock ........... Everything else. Long story short, you'd better reroll into a wizard. Warlocks are no longer superior to them in anything that matters, be it soloing, grouping, pvp or raid dps. And this is unlikely to change in the next expansion.