Warloch_Ahead: It's been on sale plenty of times from what I've seen, though I never grabbed it because it's apparently really buggy and prone to crashing (then again, I've bought games that ran just fine and there are 1 star reviews saying they won't).
I bought the discs version of NWN2 a while ago since I loved NWN and ...yeah, it was very buggy.
I had crashes with loading and cut scenes, I had bugs with various puzzles... I could never complete it. I did like the second/third expansion (can't remember, but think it was Storms of Zehir? the one that is not really like NWN at all) and it didn't seem buggy at all.
I have NWN2 complete on GoG and was having a lot of the same issues, so I uninstalled it, then I decided to reinstall it, but I didn't install STorms of Zehir ...and a lot of the random bugs I had with cutscenes being bugged and transitions never happening just stopped. For the brief time I played it, I got a lot further than I had in many of the other tries with no bugs at all. (Sadly, I have started it so many times, it is hard for me to actually play it, because I have to play past areas I have played over and over and over again, and that is one of the things I have a hard time doing.)
So, I don't know if that particular expansion was introducing things into the original campaign that it shouldn't, or if I just had something completely unrelated going on, but for me at least, NOT installing the final expansion pack seeminly fixed things.