The NWN campaign was so boring and repetitive after two chapters I could hardly go on, the only thing that kept me going was levelling up my character. The only thing that was really good was the Charwood Village area. The two expansions were much better, especially HotU.
Since you like FPSs, The Chronicles of Riddick game had a good story and great atmosphere, especially if you like the whole stuck-in-a-prison thing and you don't mind hard violence and naughty words.