Warning: May explode on use.
Engineering is a unique tradeskill that doesn’t have any particular focus. Many engineering items provide special skills that are generally only available to a single class, while others are just cosmetically nice - like a pet robotic chicken or a gyrocopter flying mount. If you like the idea of taking a profession that gives you all sorts of wacky, amusing abilities along with some useful special gear, engineering might be for you. Engineers are also the only class that can produce ammunition for guns, adding to their utility, as what they produce is generally some of the best quality bullets for hunters and others. They can also produce guns, some of which are in high demand, along with scopes which increase the power of ranged items. All engineers can choose between two specializations - gnomish and goblin engineering - which alters what recipes are available to them. Goblin engineering items tend to have stronger effects, but are more likely to have serious potential malfunctions. Gnomish engineering is the opposite - weaker effects on average, but slightly less dangerous malfunction consequences.
To balance the additional bonuses that they get, almost every engineering item has a chance to backfire on its user. For example, all engineers can make an item that enables them to teleport to certain cities like Gadgetzan in Tanaris or Area 52 in Netherstorm. If the item backfires, you might be launched high in the air and will die on impact unless you manage to use a slowfall spell or a handy parachute cloak. Your shrink ray that’s supposed to work on your enemies might backfire and hit you instead. That’s part of what makes engineering fun - you never really know what you’re going to get when you activate your equipment. One side benefit to engineers is that they get to make powerful goggles for a variety of classes and roles that are bind on pickup.
Wrath of the Lich King is bringing about some changes to the engineer in that now items that would formerly have been trinkets can be added to your equipment. For example, you can mount a Hand-Mounted Pyro Rocket to your gloves, allowing you to do 2070 to 2530 fire damage at range once every two minutes. This makes most engineering items more convenient, allowing you to get more out of the combat portion of the profession. As such, it’s becoming a more attractive profession for people to look at.