At most indifferent about multiplayer, even coop, I don't believe that the pace of this kind of game is suited for multiplayer (lot of text reading, non real time combat...).
Modding can be good, but I am rather a BG than a NWN fan.
Multilingual however is important to me, even though I already backed the project. I am a native french speaker, and I enjoy reading stuff in my language rather than english, for obvious comfort reasons. Moreover so far the stretch goals are unexciting, to the least. (more money = more game, orly ?)