For a while pre-BC, I was plagued with doubt over my class choice. I had my level 60 warlock at that time, but kept wondering where the class fit in the big scheme of WoW. In short, I was wondering, "Why take a Warlock, when you can have a Mage?" Both classes are cloth-wearing DPSers. Other than specific encounters where Banish or Enslave Demon were required, I couldn't think of much that set warlocks apart from mages.
Need AoE? Mages did it better. Need CC? Polymorph is more reliable. Need burst damage? Mages were faster. Need food and water? Ask the Mage. Debuffs and DoTs? Sorry, but warlocks took up too many of the eight debuff slots, pushing off those that people do need, like Sunder. Sure, warlocks were useful for summoning the occasional latecomer, but would you have really noticed the difference if the Warlock in your party or raid was replaced by a Mage?
Things have come a long way for warlocks since The Burning Crusade - maybe too long a way for some folks - let's look at some reason why you may enjoy the Warlock class:
If you like to blow things up, or watch them waste away over time, this is the class for you. With the debuff limit increased from a measly 8 to 16 and finally to a glorious 40 currently, warlocks can realize the full potential of their DoTs and debuffs in big group situations. Warlocks can also nuke like the best of them, especially if you're bent on Destruction.
The most important thing about our DPS potential is that it is sustainable over long fights through a combination of Life Tap and healing. Like warriors, rogues and feral druids, warlocks can deliver an almost inexhaustible supply of damage. And we're the only mana-based class that can do this. With some light healing, warlocks are a reliable source of damage for long fights.
Soloability and survivability
One of the Warlock's key stats is Stamina - which translates into our ability to soak some damage, even if we wear our pajamas(cloth) into battle. Warlocks also regenerate and heal themselves with drains and healthstones. Soloing warlocks have a number of tricks to survive encounters that turn ugly: soulstone, voidwalker sacrifice, and even deathcoil. Warlocks may have a relatively complex set of abilities, but they are really an ease and joy to level and solo. Thing is: we're never short of options; as a Warlock player, you only need to know these options and use them at the right time.
Unlike some classes where certain talent trees are more suited to some forms of gameplay, Warlock talents are all generally viable for PvE, PvP, soloing and everything in between. Optimizing the warlock build is really an exercise in splitting hairs and the talent tree you choose lies entirely with the play style you like. Warlocks certainly don't enjoy the versatility of druids, but within the confines of the DPS role, we have a wealth of options to make things go BOOM.
Lore and look
For roleplayers, the Warlock class offers a lore-rich option to be evil, power-hungry, or just plain eccentric. The look of the class just drips flavor: a bustier-wearing succubus, fiery class mounts, shadowy masks, shoulders with skulls impaled on spikes (probably gnome skulls), wings!! (see above). If you're a player who likes a dark fantasy avatar that looks foreboding and menacing, roll a lock.
Why not a lock?
So I spoke to some people on why they don't have a Warlock. Now some of these are experienced players who aren't new to leveling multiple characters. Many indicated "play style" as a reason.
Some players do not want to deal with pets at all, citing the popular notion that hunters and warlocks are "easy mode" classes that let their pets do the work for them. I prefer to see pets as physical extensions of our abilities, much like a Shaman's totems. Just because they can attack on their own does not mean that hunters and warlocks can sit back and watch the show. Incidentally, if a pet does all the work, the dead mob does not drop anything!
Some have indicated that DoTs are boring, and they prefer the exhilaration of nuking or hacking their targets down as quickly as possible. "I prefer the POW! of mages," a friend explained. At lower levels, warlocks do seem to playing a game of health management, of their own and their targets', rather than using any "shock and awe" abilities. While warlocks can whittle down multiple targets at the same time, our pace seems more deliberate and lacks the flash and dash of other DPS classes.
At later stages of the game, however, warlocks get more options in terms of nukes, both instant and those that take an eternity to cast. Destruction warlocks are the nuke monkeys of the class, with access to shadowburn, conflagrate and faster, fatter shadow bolts. So hold on to your trigger-happy fingers, young warlocks, your nuking days will come!
It's interesting to note that some players have an irrational dislike of warlocks, even when the option of rolling and understanding one is right at their fingertips. "There are too many bad warlocks", "Warlocks are OP!" are common reasons cited.
Lore-wise, warlocks aren't exactly well-liked either, consider that one of our kind, named Gul'dan, basically started this whole war. In fact, according to this great RP resource site, "role-playing a warlock is not recommended for those who are sensitive to mental or emotional abuse, as these characters will likely get insulted or harassed at some time during their career." Hmm.
Why did you roll a warlock? Why did you not roll one? Let's