Risen 2 and Game of Thrones are both the same. Average rpg's and they both have flaws. I couldn't say which one to buy so just buy both as they should be cheap by now.
I haven't finished the game yet, played only about 10 hours so far and I've been enjoying it. However, I would not call this game "average." In my view, the problems with this game are huge, and I cannot recommend it to anyone who is not already a fan of ASOIAF. I think the flaws must make this game nearly unplayable for those who are not fans of the franchise.
The game is set 15 years after Robert Baratheon defeated the Targaryens and took the Iron Throne, so there is some overlap and while it is not clear how much GRRM was involved in developing the story, it is clear that he had some influence in his capacity as consultant, as it seems to fit very well into the framework of the world and characters he created. The story is well written, the majority of the voice performances are excellent. ASOIAF fans should not pass up this opportunity to experience another small piece of the overall story.
My main gripe with this game is that you have relatively large level environments, with lots of NPCs and clutter (such as Castle Black and the city of Riverspring), but you can't interact with anyone or any of the objects. Even Dragon Age 2 permitted a bit more interaction with NPCs. Out of hundreds of NPCs in Game of Thrones, you can only interact with .001% of them.
If only they would release some sort of mod tool for this game, I'm sure there are some dedicated and talented fans willing to flesh out the world and breathe life into all these window dressing NPCs. But I'm guessing hell will freeze over before they release mod tools for this.
As for the combat, at first it seemed like I was just passively watching my character auto-attack most of the time; however, once I got the hang of it, I learned there is a lot more to it and it is actually kind of fun.
I haven't played all the different character builds and but unfortunately there doesn't seem to be a great deal of class differentiation, at least not in the beginning. The game is structured in a way that you alternate between playing two different characters in different parts of Westeros, Mors Westford of the Nightwatch dealing with an invasion of Wildlings and Alester Sarwyck, an exiled son of the Lord of Riverspring, returned from Braavos to attend his father's funeral.
You choose what's called a "combat style" when you start playing each character from among three options, and each combat style has a different proficiency with certain weapons and different "stances" or class ability trees. You start with one stance, which includes a perk tree of abilities you can learn at each level up, and when you reach level 7, I believe you can choose one new stance from three optional second stances.
Mors Combat Styles
Magnar: dual-wield, starts with Frenzy, can choose from Berserker, Domination or Intensity for second perk tree
Landed Knight: sword and shield, starts with Defense stance, can choose from Elite Knight, Domination or Frenzy for second stance
Hedge Knight: two-handed weapons and ranged, starts with Domination, can choose from Elite Warrior, Defense or Frenzy for second stance
Alester Combat Styles
Water Dancer: dagger or short sword , starts with Intensity, can choose from Master Water Dancer, Dexterity or Frenzy for second stance
Sellsword: long sword, starts with Assassination, can choose from Hardened Killer, Frenzy or Defense for second stance
Archer: ranged weapons, starts with Dexterity, can choose from Elite Archer, Intensity or Assassination for second stance.
As you can see, there is too much recycling and overlap among the second stances available for the various combat styles, and this is another major problem with the game. For example, combat with Mors as a low level Hedge Knight did not feel very different from combat encounters with Alester as a low level Water Dancer.
In addition to the combat styles and stances, Mors and Alester have separate Hero Ability Trees. Mors is a warg and his abilities have to do with various attacks he can cause his dog to carry out. Alester is a Red Priest and his abilities have to do with setting his weapons on fire and causing fire damage or reviving allies with R'hllor's fire magic.
The warg possession gameplay was actually quite interesting. As a dog, you can pick up on various scent trails to find clues or hidden objects.
Also, whatever they paid to license the music cues from the TV series, it was well worth it. The score helps a great deal to establish the tone and setting of the game.