The Forces of Warmachine and Hordes: A Breakdown

A small breakdown of the forces of Warmahordes:

Cygnar: The boys in blue, Cygnar are a favorit for a lot of new players.
Background: Cygnar is an industrious nation with advanced technology. Their very reminiscent of Britain and America during the industrial revolution. This is reflected by the fact their military has recently undergone massive shifts from traditionally poorly equipped warriors armed with swords and spears controlled by noble lords, to a well disciplined, highly trained professional force, each armed with the most advanced weapons the state can provide.
The mages and wizards of Cygnar have mastered the use of lightning as a weapon of war, and their enemies know dread when the skies darken and the roll of thunder his heard.
Play Style: Cygnar is normally known as the shooting faction, and they do indeed have a monapoly in that area compared to most other factions. However they have many great melee units and models, including the fearsom Stormblades. Cygnar's Warjacks are fast and very accurate in melee as well as at range.

Khador: The Reds, Khador is a strong 'brick' faction with few frills.
Background: Khador lies in the frozen north, its people are hardy and warlike, large of stature and proud in bearing. Khador controls a large amount of land, but has a relatively small population. Ruled by their Empress, Khador has recently launched aggressive attacks at its neighbors, completely occupying the nation of Llael and encroaching upon Cygnar.The battle wizards of Khador can bring the frozen winds of their home with them to battle, freezing the enemies of the Motherland in their tracks.
Playstyle: In a game typified by units giving bonuses to other units and synergy, Khador is unique in that its armies are largely self sufficient. Khador has powerful shooting and melee forces that can usually get the job done without much help. Its Warjacks are a byword for tough and can survive a massive beating.

Cryx: The Nightmare Empire, the undead forces of Cryx can be a headache for anyone to deal with.
Background: Cryx is an island nation of the undead. It is controlled by the Dragon Toruk, who is worshiped as a god by its inhabitants. The nation periodically raids its neighbors. Many have suggested a sinister pattern in these raids, though nothing conclusive has been unearthed... The necromancers of Cryx can literally steal the souls from their enemies and bring down a black rain of acid from the skies.
Play Style: Cryxian units are typically fast, hit hard in melee or have magical shenanigans. However, they lack the ability to have a strong ranged-game and are usually quite fragile. They also have the unique ability to 'de-buff' (weaken) enemy units. Cryx usually requires more finesse to win with than an army like Khador.

Protectorate of Menoth: Religous fanatics, their enemies must convert or die.
Background: In the beginning, the god Menoth created humanity and gave us the gifts of writing, civilisation and fire. But, humanity has turned its back on the Creator and worships weak gods. This must be rectified, and the armies of the Protectorate march forth to convert and purge. The priests of Menoth can call down fire upon the enemies of their god, and can perform small miracles to shield the faithful.
Play Style: The Protectorate is very much an army of synergy. Individually many of its units are inferior to those of other factions, but together they create a force greater than the sum of its parts. There is a very strong theme of fire throughout their army, and the Protectorate can set entire enemy armies ablaze. The Protectorate is mostly a melee centric force, but does have several strong ranged units.

Retribution of Scyrah: The Elves of Warmachine, the Retrebution is a highly flexible force.
Background: The Elves have long been separated from the wars of humanity in their nation of Ios. But a strange affliction has taken hold of their race; more and more elves are being born without souls, and their gods are literally dieing. The Retribution of Scyrah is a radical group that has determined that human magic is the reason for the withering of their gods and the Soulless births. Their solution? Kill all human wizards.
Playstyle: The Retribution is an extremely flexible and fast force, its Warjacks (called Myrmidons) exemplify this by being equipped with ranged weaponry as well as being more than capable of mixing it up in melee. Retribution battle-mages can alter the state of the battlefield by moving enemy or friendly models, setting up charges from positions thought secure only a few moments ago.

Mercenaries: Whether its adding a few needed models to a main faction, or taking to the field as an entire army, Mercenaries can get the job done...for the right price.
Background: There are many different sub-factions that fall under the category of Mercenaries. The Dwarves of the Searforge Commission march from their ancestral holds to secure trade routes and gain an insight into the wars of man. The pirates and sea dogs of the Talion Charter rule the high seas. The resistance fighters of the Highborn Covenant fight to free the nation of Llael from Khadoran invaders. The private army of Aseth Magnus moves to replace the king of Cygnar. Finally, the honored Stealhead Mercenary company fights simply for coin.
Play Style: Mercenaries can be used in two ways. The first is to simply add a mercenary model or unit to one of the other factions. This can be done to provide a unique angle that the faction in question might not be able to provide. The second is to field an entire army of Mercenaries. Mercenary armies are very flexible and full of character, easily able to take on the other main factions using synergy and cleaver tactics.

Trollbloods: Tough and rowdy, the Trollbloods are a force to be reconed with.
Background: Trollkin are large, intelligent humanoids that have been uprooted from their ancestral homes by the wars of the human nations. Though lacking in the technology that humans can produce, they more than make up for it with natural toughness, and their potent allies; Full-Blood Trolls. Ten tons of mean muscle that's always hungry.
Play Style: Trolls are tough (each model in the army literally has a special rule called Tough) but slow. They are also extremely potent in melee. They have a simplistic, but fun playstyle typified by the simple expression: Axe-to-face.

Circle Orboros: Druids from the wilderness, they must destroy civilisation to save the world.
Background: There exists a god named The Devourer Wurm, or Orboros. The essence of all that is, was and shall be, the Devourer is the world and the world is the Devourer. The Devourer Wurm represents all that is primal and pure in nature, but civilisation is his anti-thesis. When Menoth provided mankind with civilisation, the Devourer attacked him, and for thousands of years the endless battle between Orboros and Menoth has raged, echoed in the hearts of mankind. Should civilisation spread to far, Orboros will return from his war with Menoth and destroy all of humanity. This the Circle of Orboros cannot allow, and thus they must destroy civilisation to help save it. They are the wardens of the apocalypse.
Play Style: The Circle of Orboros is a Guerrilla army that strikes swiftly and then vanishes, silencing its enemies before they can strike against them. It can call upon the powerful Warpwolves and Skinwalkers to rip apart its foes, as well as druids mastered in mystical arts. The army can teleport across the board, rip the enemies heart out, eat it and then retreat back to the safety of the forest like it never even happened.

Skorne: Cruel invaders from the east, the Skorne Empire enslaves all before it.
Background: Far away in the eastern deserts, a race known as the Skorne created an empire founded on the backs of slaves, its machinery oiled by blood shed in bondage and pain. The Skorne Empire now march to subjugate and enslave the weak powers of the west and take their riches for themselves.
Playstyle: The Skorne are a highly disciplined and professional force, with capable melee and ranged infantry, as well as powerful warbeasts. While their armies are considered slow by Hordes standards, their heavily armored. An interesting mechanic for the Skorne is that many of their units get more powerful from the pain inflicted on them, or those nearby, harnessing the power of their souls.

Legion of Everblight: The personal army of the dragon Everblight seeks to take over the world.
Background: The dragon Everblight has corrupted a race of northern elves named the Nyss with his blood, and plans to use this army to slay and devour his siblings, increasing his power to godlike proportions.
Playstyle: The Legion of Everblight is very fast, its infantry mainly consisting of elves. It has a very strong melee game, but better shooting than most other factions. Its warbeasts are powerful dragonspawn created for a specific function. Many Legion models suffer from low armor however, but their high Defence makes up for it.

Minions: The Mercinaries of Hordes. Will fight for food.
Background: The wars of man have created new opportunities for races hidden among the wilds. The tenacious Farrow, a race of humanoid boars and the ferocious Gatormen have appeared in armies larger than anyone thought could exist and are fast proving to be more powerful than anyone could have predicted.
Playstyle: Currently there are only two Minion armies, the Thornfall Alliance (Farrow) and Blindwater Congregation (Gatormen). The Thornfall Alliance has a surprisingly strong shooting game, with some great melee support from the warbeasts. The Blindwater Congregation on the other hand, has virtually no ranged weapons at all, but is extremely powerful in melee.