One thing that upsets me is, Pc users corrected the bug with the Dark Brotherhood Mask working on all Male Characters. Also, They created a awesome Acrobatic and Unarmed perk tree.......

Pfff, Nightingale armor looks more bad azz

Honestly, one of the bugs that upsets me the most is also one of the most minor overall:

The Jeweled Pitcher doesn't appear in the Ragged Flagon Cistern's trophy case after you do 75 Radiant quests.

That takes a long time to do, and to not even get the full rewards for it, even if those rewards are only aesthetics, drives me nuts.