Warriors can be a raging berserker or an iron-clad juggernaut, capable of withstanding tremendous attacks while protecting their allies from harm. They have a wide variety of attacks that do everything from cripple their enemies, to dealing massive amounts of damage in a single retaliatory blow, and enhancing their allies' fighting ability with battle shouts. They excel at fighting multiple opponents at once, gaining rage from every blow dealt or received to unleash their attacks. Warriors are a versatile class with a variety of play-styles to choose from.
The Warrior can be a defensive, shielded tank, a damage-dealing powerhouse (DPS [Damage per second]), or a mixture of the two. Their abilities obviously pertain to the art of close combat; their stances carry with them different moves for different situations and party setups. All in all, the Warrior is one of the prime candidates to capture and hold the attention of creatures while they die to sword and spell.
Warriors may also wear Plate armour, and duel wield weapons, 2 abilities some classes lack, making them very well suited for their roles in a raid, or Battlegrounds.
Since the release of Cataclysm, the Warrior class has become the first non-hero class to be open up to all twelve races (which incluce the new Goblin and Worgen races).
 Pros and Cons
With the appropriate gear, warriors are potentially the best tanks in the game. They have various ways to mitigate damage, several aggro generating abilities and even a few "Oh shit" buttons such as Shield Wall.
Despite having many aggro generating abilities, their initial aggro generation when engaging targets isn't as great as a druid's mangle. I guess this is considered a con but tanks rely heavily on their gear. If they don't have the ideal gear for a certain boss, they can't do it unless they have some pretty good healers.