I just finished the game ,MoB seemed about same length as Bioshock maybe slightly shorter ,I did not rush the game,can't really since you have puzzles etc.. so they do slow you down.
I only had one crash through the entire game on my Vista x64 Home Premium near the beginning when it was loading to a new area,unfortuantely for me my middle mouse button in game stopped working shortly after this for camera rotation, so I went to options and configured it to use left mouse button and hold,I also submitted the problem in their issues thread,dialogue I only found one bug towards the end(can't go into that without spoilers but its not a story breaker).
There are some puzzles in the game which you'll like or hate,took me a couple of hours to figure them out .
Overall good expansion ,nice interesting story with plenty of dialogue,AI needs improving,camera angles/controls I felt could also be improved since I was never quite happy with them throughout the game,did not feel natural like it does in other games.
I also felt too much special effects with magic spells,no fun when 90% of your screen is bright white due to various lighting,magic spell attacks etc and you can't see your party .You probably saw my post about game balance ,this game is going to be either hard or easier depending how your party is setup(level wise too) and what area you go to first(NWN2 main game seems to break you in more gentley,unlike MoB which can give you a challenge) some fights are tough,only tips I can really give you is max out your party , (I had a cleric,spirit shaman, red wizard and my paladin) early in the game I did not max out my party and ventured into the harder area by accident ,there are more tips I can give you but unfortunately they are to do with the story.
I enjoyed the game more then I did Bioshock and story is better then NWN2 so think that says it all.I'm looking forward to replaying the game once a few patches are officially released.FYI my 7800GT card at 1680x1050 with shadows off did get some pauses with heavy battles but nothing serious.
There are known issues with this game when it comes to bugs,ie installing game with wrong version of main NWN2 can cause serious issues,there are more bugs/problems just check their official MoB issues thread.Is the game more polished then main NWN2?..I think this depends on the individual and his hardware,personally I had no mouse issues(middle mouse button ,camera rotation) with main game unlike MoB,balance I felt in NWN2 main game was better(to be fair more patches have been released for main game).
MoB will be a fine game once a few more patches are out to fix the various problems people have had and also to polish the game,yes its playable as it stands but can be improved which will obviously happen with time and patches.
Btw my Jade Empire Special Edition arrived today so good timing

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