Gears of war 3.
Finally finished it today, I must say I really enjoyed it. It's not my favourite pick of the three, as no2 still ranks top imho.
I had 2 game breaking bugs, first one is where hammer of dawn fires randomly, that was poorly scripted and really annoyed me. second one was chapter just after that, my character end of a cut scene just kept on dying on load for no reason so I had to restart chapter.
I played on hardcore which felt more like normal to me, some places was evenly difficult where as some was just silly and others just too easy. End bad leaves much to be desired, I failed first 4 times, but 5th I just flew through it and it was over before I noticed any challenge.
All in all it touches 80, but is more like 75/100 I would say.