Sith Warrior

Wondering about which crew skills to pick? Here's a list of the crew skill bonuses Sith Warrior's companies have.
(Note: "eff" stands for efficiency, "crit" for critical chance. Efficiency is a direct percentage that is reduced from each task's duration.)

Vette: +5 Treasure Hunting crit, +5 Underworld Trading eff
Malavai Quinn: +10 Armstech eff, +10 Diplomacy eff
Jaesa Willsaam: +5 Archaeology eff, +5 Synthweaving crit
Lieutenant Pierce: +10 Cybertech eff, +2 Investigation crit
Broonmark: +10 Scavenging eff, +2 Bioanalysis crit

No bonus to: Biochem, Armormech, Artifice, Slicing

Other classes:
Bounty Hunter
Imperial Agent
Sith Inquisitor

To add to what Ghulthar said, it plays like a warrior from WoW in terms of the type of abilities it has (melee class with a charge, AoE taunt, cleaves, execute, etc), although in terms of its resource, I would say it plays like a hunter (as of 4.X).

Sith Warriors (and all the other classes, for that matter) have no auto attack, and for that reason your rage doesn't just build up by passively standing next to an enemy like in WoW through an auto attack. (Rage in ToR is static while in combat) The class has a filler move (Assault) that can be used like a hunter's steady shot (without a cast time) to generate rage while the rest of the attacks consume rage. So (disregarding the rage not passively generating slowly and the filler move being an instant cast) in essence the resource system requires you to balance between rage building/dumping moves like a hunter.

A compilation of companion order of appearance -

Vette - Korriban (level 8ish) Ranged DPS
Droid - Drommund Kaas (level 15-16ish) Pure crafting/gathering bot (does have heals, but utterly useless - also his name escapes me, so he'll just be "droid")
Quinn - Balmorra (level 20-22ish) Ranged Healer/low DPS
Jaessa - Tattooine/Alderan (level 30ish) Melee DPS
Pierce - Taris (level 35ish) Ranged Tank/DPS
Broonmark - Hoth (level 38-39ish) Melee Tank/moderate DPS

All levels of obtaining are based on the pace at which you complete the story missions. Personally, I finished a planet's story mission as I finished the other missions.

Warriors are quite powerful when played right but require a little more patience than other classes to get the hang of.

Not only do they have a Force Charge, they also have a defensive type ability that works the same called "intercede". This will allow you to jump to the aid of friendly players or help you travel across the maps at great speed when used in chain with Force charge.

Great examples are in Huttball and you want to get out of one of the pits. You can either charge an enemy on a higher platform, or jump to an ally. Or even both if you get knocked off.

Taken from SWTOR official website www.swtor.com

CHAMPION OF THE DARK SIDE

An unstoppable force of darkness, the Sith Warrior is entrusted with the task of destroying the Empire’s enemies and enforcing Sith domination across the galaxy. The Warrior channels the destructive emotions of fear, anger, and hatred to purge weakness from body and mind and become a being of pure, brutal efficiency.

Destined to eradicate the incompetent chaos created by the Jedi, the Sith seek to rule the galaxy through power and intimidation. The armies of the Sith Empire are trained to accomplish this task, but they require the leadership of bold Sith Warriors—loyal and mighty overlords—who will drive them to conquest and victory.

These cold-blooded conquerors waste no time with cunning manipulations and carefully-crafted plans. Sith Warriors crush their opponents and stride toward their goals with dreadful determination, leaving ruin and annihilation in their wake. Emanating awe and terror at every step, they accept nothing but absolute obedience from their followers. In turn, Sith Warriors can serve as loyal subjects to their own dark masters, often surprising enemies and allies with their rigorous honor and perfect discipline.

Whether they align their ambitions with those of the Dark Council or become renegades in pursuit of their own goals, they are never far from the action. Their fierce hatred of the Jedi keeps Sith Warriors at the forefront of any conflict with the Republic. The passion to eradicate the Jedi Order fuels many of their actions, but that does not make them single-minded fools.

Ultimately, the destiny of any Sith Warrior is his own to choose… and woe to those who would stand in his way.

WORKING WITH OTHERS

A natural leader in any context, a Sith Warrior inspires both fear and undying loyalty into his followers and allies. Though they rarely exercise patience for incompetence or indecisiveness, Warriors have realized the importance of strength in numbers in their war with the Jedi, and have learned to accept and sometimes even encourage their comrades, whether they are like-minded Sith, ruthless Bounty Hunters, or others who embrace the darkness.