I play it extensively. Did you have any particular questions? Did you want a run down of the game?
Warmachine, and Hordes, are skirmish games that are easy to get into. If you like collecting, you'll probably end up with the same cost as other games if you get the entire line for you army, but you'll be playing all along the way. All you really need to start is a Warcaster and 2 Warjacks, but that's just a basic starter. The 2 player box set is actually a really good deal since it gets you much closer to the normal sized game of 35 points.
I've played almost every faction, and fought every one. My current armies are Retribution and Cygnar, although I used to play Trollbloods from Hordes.
The core mechanic of warmachine is the interplay of the Warcaster, basically the army's leader akin to a King piece in chess and his magical ability in the form of Focus, which is then used to cast spells or power up his Warjacks, big steam powered robots with magi-tech brains (called cortexes) that are psychically bonded to the Warcaster. Every Warcaster has usually 5-6 focus points, and much of the decision making is choosing where to spend it since each spell costs focus, but focus can also make Warjacks incredibly deadly.
Then you add on other unit types like infantry, artillery weapons, solos and special characters, each of which have their own special ability, and the interactions become quite fun.
Most games the objective is to kill the enemy Warcaster, so you'll have to get used to the idea of sacrificing things to line up the chance to get the kill in, which isn't easy.
Hordes is a companion game to Warmachine, it uses mostly the same rules, but instead of steam powered robots, you have fantasy beasts that are magically enraged to generate fury energy that their Warlocks tap into. So if you like big living monsters instead of steam robots, that's another option.
Warmachine factions breakdown:
Cygnar - "Good Guys." The most highest tech faction in the game. Also recently attacked by every single other faction, and on the verge of a civil war/coup. But overall, they're. They're themes are supreme ranged firepower, lightning/electricity weapons, and a solid core of all around warjacks.
Khador - Basically Soviet Russia trying to conquer the Iron Kingdoms. Lower tech, but in a sort of outlandishly low tech deadly. They can't make many cortexes, so they only put them in some of the most heavily armored and hardest hitting, but slowest, warjacks. Their infantry makes up for this with a great deal of mobility interesting tactics.
Menoth - Catholic inquisition with steampunk inquisition, and an obession with fire. Their warjacks are slightly slower than cygnar, and not as hard hitting or armored as Khador, but they make up for it with divine buffs they can put on them. The whole army is built around units buffing each other or other kinds of interplay between abilities. You've got a mix of cheap zealots, to holy knights, and a lot of denial style specials.
Cryx - Undead meets evil mutation causing dragons meets steampunk. This isn't your traditional army of undead with shambling zombies and skeletons. This army tends to have fast warjacks that are a little harder to hit, but lower armor. They are the only ones with lesser warjacks, the bonejacks, and a plethora of arc nodes that effectively extends the range of the warcaster's spells without risking them. Most of the army is actually built around speed, or nasty unit-wide abilities.