Having gotten this game for a friend and subsequently discovered that it also works on Vassal thanks to some modules designed by a few clever-boots, I've played it a few times recently. The connection with the old favorite Diplomacy is not to be denied. Like Diplomacy, it's primarily about lying and manipulating, with the actual mechanics of the game being secondary to these tricks, temporary alliances, and other such friendship-ruining agreements.
The game reminds one of Birthright though of course with less detail on the actual ruling of places and more emphasis on warfare. Its alternate-history Westeros is one in which the families of the land more or less stay together and don't fight each other (Renly and Stannis, for example, are both commander cards in the Baratheon deck regardless of their disputes in the books) and in which Eddard Stark was never beheaded. That's ok, though, because the game is FUN AS HELL. Instead of writing your orders down on a slip of paper like Diplomacy, you put face-down markers on the table and then everyone flips them over at once. Even once you've declared your orders, you can still choose WHERE exactly you want to march that dangerous army, eliciting the possibility of further diplomatic talks before your troops shred the much-needed provinces of a neighbor.
Also interesting (and by interesting I mean great) are the uneven starting positions of the great houses. The Starks, for example, have the vast and unpleasant wasteland of the north at the beginning of the game. On balance, however, they are only adjacent to one house. The Lannisters, on the other hand, have a clear road to the heart of the kingdom where all the finery of the realm awaits them... but they are surrounded by other Houses and an alliance against them is likely to form early. The play styles of each house are markedly different, as are the abilities their various cards give (Kevin Lannister makes footmen as valuable as knights, meaning Lannister armies will tend to allow more footmen in their ranks).
Rarely is the game measured as a slugfest between armies. Victories or defeats on the battlefield must be followed by sound strategy on the rest of the board else you will be certain to lose. I was playing the Lannisters and the Baratheon and Stark players (there were three of us) pushed me back to Lannisport and then took it... and meanwhile, the rest of my armies were sacking the central kingdoms and the Bay of the Ironmen and I won by taking my 7th castle with Stark wolves baying for blood at my very doorstep.
The influence tracker is a great way to represent complex political realities within the simple world of the game. It shows how close each house is to controlling the "legitimate king," which presumably changes as the influence changes, to controlling the most important and warlike fiefdoms of Westeros, and to commanding the court of the king. Each of these things alter the way the game is played. Holding the Iron Throne allows you to break ties and go first. The Valyrian Steel Blade (fiefdoms) grants you bonuses in war, and the Messenger Raven (king's court) allows you to change some of your orders AFTER everyone has committed.
The wheeling and dealing necessary to win the game is a cold business. As players fall behind, it behoves the smart and right devious lord to recruit them into his cause and promise to shield them as they rebuild. In this way, their meager remaining forces can be put to good use. In one game I forced a shattered army out of the Eyrie and southwards towards King's Landing... thus infuriating the Baratheon player and causing her to turn, not on me, but on the Lannister player who's forces were moved by treaty.
Well, when you play the boardgame of thrones, you win or you die.