Game Of Thrones uses the same combat mechanic and presentation of pretty much all of the recent Cyanide Games games. So there's the slowdown ability for you to take strategic decisions in combat, and you (usually) have two characters that you control. One is focused on crowd control and healing, one is focused on one-on-one fights and stealth.
And all of this is set in the Game Of Thrones universe, which I like very, very much. There are (side)quests to finish, secrets to find, people to fight, all the while following two interesting stories that come together near the end of the game, which should take you 15-20 hours if you play normally. If you rush it's a few hours less, about 12-15 hours.
The graphics are good, faces are a bit messed up and out of date though, and same of the environments lack finer detail and variety. However, the atmosphere is accurate.
The voice acting is mostly solid. I heard a few sentences here and there that were spoken without any passion. Nothing major, but it did detract from the experience a bit. The music, on the other hand, is excellent.
Game Of Thrones is a good game, that could've been much, much better with a little extra work and polish.
If you don't know Game Of Thrones then I suggest you skip the game (but you will miss out on the better stories, mind you), otherwise give it a try. You probably won't be disappointed, but let's see what Telltale Games will come up with first. I have high hopes for their game.