NWN2: Mask of the Betrayer - Reviews @ RPG Codex, GameZone

RPG Codex is pretty quick off the mark with a review of NWN2: Mask of the Betrayer. There's no score as usual for the Codex but it seems they really liked it:

That’s where the game starts to shine so brightly that you completely forget about any flaws the game has and get lost in a well crafted gameworld. It’s like a dream come true – a non-linear game loaded with well-written dialogues, interesting quests, more choices than you can handle, and enough consequences and to make the game highly replayable. It’s hard to imagine a better feature list.

...Meanwhile, GameZone has short review with a score of 8.3/10:

This is a truly solid and enjoyable expansion. It can be very hard on the player, but part of the magic of the NWN series is that it requires you to think about what you are doing. Graphically the game does the job, the sound is well done, and the story is very strong. The original NWN2 had a few problems, something that has been addressed with this expansion. While the game has a few problems, it still is a reward for those who have played NWN2 and hungered for more.