The first is the "Esbern's Potion" glitch, where the perk is never given to you. Personally, I have my characters wait at the point before I meet Paarthurnax, because I want to be able to get this perk from the blades before they refuse to talk to me because I won't kill Paarthurnax for them.

With all the rumors that Dragonborn will take part at some point in the main quest, I would REALLY like to see this fixed, seeing as my main quest is on hold because of it.

The second bug is everything not cleaning up properly. By that I mean all the weapons/shields from your battles across skyrim still laying around. Many of them floating in the air, just taking up memory and slowing your game down. There's also many dead bodies that never clean up, Ulfric Stormcloak being one of the more ridicules ones. Finally ash piles never seem to clean up either, despite a fix specifically saying they do now. The ash piles were never a problem for me, as I could just, you know, not make piles of ash. Since the release of DG though, I HAVE to drag Serana around for bits of the quest, and she just LOVES to raise anything she can. A wolf?! YOU CAN'T POSSIBLY HANDLE THAT ON YOUR OWN DRAGON BORN LET ME RAISE THIS MIGHTY BUNNY TO ASSIST YOU!

The last bit was obviously a joke, I have no problem with DG or Serana, but it did result in several ash piles permanently taking up space in my game.