*I'm going to keep updating as I find new issues*

I just started a new DawnGuard game and already I've had to uninstall/reinstall it twice!
I couldn't get the alchemy lab in the breezeway home in Whiterun & when visiting the mages college for the first time the girl that escorts you up the bridge stopped and wouldn't light the second energy beacon, turned around and walked back to the beginning - both of these issues were fixed by uninstalling, get the lab/entering the college, then reinstalling DG. As such I'm scared to even start the DG quest line because I may have to do this again when I encounter another jacked up glitch...

Other problems I'm having are;
- The Vitality Drain shout glitch where I have 3 different version of this shout in my list - two of them keyed off of the Marked for Death shout words.
- I have a 'return to Skald to collect bounty' in my quest log that can't be highlighted or turned in when talking to Skald in Dawnstar - had to do with a quest to kill a giant for him which also doubled up in the quest queue but both cleared out when I killed the giant and collected one reward, but this second one won't clear.
- Dragons will sometimes fly away after their lifebars are empty and they should be dead, chasing after them yields no corpse - I have to reload from the last save and wait for the dragon to land before attacking/killing them so I can loot the corpse and collect a soul...
- In various tombs using aura whisper I can see that there is a draugr "hiding" in a sarcophagus but he won't come out even if I shout/cast a spell/attack/jump up and down, etc. This has happened a few times in a few different locations, really it means one less enemy to fight each time, but still.
- Lots of NPCs in nearly every city will disappear and reappear in a different location, sometimes close to where they were, and once the quest marker jumped from right in front of me to across town in Whiterun when the NPC guy I was returning a sword to glitched like this.
- I like bows (and really like that there are dragonbone bows and arrows!), and the killshot animations are pretty fun to watch with the bows now, but a couple of times its gone into the animation and not killed the target and the arrow just disappears - by the time I regain control the creature I was attacking is pretty much on top of me beating me down already...

I'm sure I'll run into more as I progress farther, I'm trying to avoid previous issues like getting the hanging gardens book before the quest, or the briar heart glitch in repairing the phial, and I'm making sure I have enough money for the house in Markarth before I even go there and talk to the jarl. Great game, but svcks when little things like this lock it up and ruin it for you.

Most of your issues have been discussed in detail in other theads, suggest you search this forum with some keywords, and you'll get a few answers, especially some of the shout bugs.

Good luck.

Oh I'm sure its nothing new for a lot of people, just as I'm sure I'm going to run into more - when playing the original game I was level 58 and got the bug at the twilight sepulcher where I got stuck in the room after nocturnal left and along with the briar heart, hanging gardens, and markarth home nonsense I got frustrated and put the game on the shelf. Only recently with the DG release have I started playing again from the beginning, thinking that a patch or two and a DLC should have cleared a lot of issues up, and was just posting my experiences so far.
I like skyrim even more than FO:3 or even FO:NV (both of which had their own bad bugs as well) but it gets rather tiresome to put in the time and effort on a quest only to have it fail from some stupid glitch. And then another one, and another one...
Oh yeah, I haven't even gone near the bard's school yet because I don't want x-amount of weight from stupid instruments I can't get rid of on me, don't even know if thats fixed but that quest line wasn't very exciting anyway from what I remember.

Don't remember the Inn's name but it is a little ways West of Windhelm near a small pond (it is the Inn that you have to kill the Orc writer at for a Dark Brotherhood quest), I randomly stopped in there before exploring nearby ruins and asked the barkeep for work, he gave me a bounty to go off some bandit boss and away I went. I noticed that the quest was double queued, I killed the bandits and received the message to collect my bounty from Skald, again doubled in the quest log (and I still have the other one from the giant stuck there).
Talked to Skald again, got my payment, quest registered complete, but only one of the quest lines dropped out again. I now have two 'return to Skald to collect bounty' quest under Misc that cannot be highlighted or removed, and talking to Skald won't clear it out either.
So it appears all bounty quest with this guy are broken like this. This isn't a game breaking problem by any means, but it is another stupid problem nonetheless.

Oh, and there is an ash pile in Whiterun that has been there since my first visit and a vampire thrall attacked me, that was at probably level 12 or so and I'm now 41.

So found another bug, not game breaking and I actually got paid for it...
I completed my second "special" assignment for the Guild where you meet the contact and do their job to help set up the Guild in another city, upon my return to Delvin he had the dialogue again for turning in the first special assignment as an option again, selecting it gave me the same kudos and a payment of gold!
On my third special assignment now, curious to see if I'll be able to collect on the first two again upon my return.

Yep, it appears if I'm away from Delvin for a few days and return to him he gives me all the of the options for the finished special assignments endings conversation threads again - clicking through all of them will randomly net me another 500 septims.

Also, for some reason I had to visit some little hole in the wall for part of another quest to kill a bandit leader and I found a book, children of the sky, and just now as part of the college quest did I get this 'go find a copy of children of the sky'. Even though I already have this book, it won't register and its telling me to go to the retreat that is already marked as 'cleared'...

Yay skyrim! God [censored] it Bethesda, fix these issues already! This is an old one even.

Apparently there are a couple different copies of this book in the world, I'm going to try to track down another one and see if that will work for finishing this quest and allow me to drop the 'quest item' copy I have in my inventory already once done...

Windhelm marketplace exploded!

Over by the blacksmith shop and the alchemy shop, those 3 or 4 vendor stands in the corner; all of their displayed goods have exploded outward and are stuck in the air. It looks like a scene from the Matrix! Tried reloading into the city, tried reloading a previous save... nothings fixed it and the only similar problem I can find are references to peoples household goods erupting all over.
I also tried to be helpful and 'grab' the items to move them back in place, but as soon as I tried that the guards yelled at me for stealing and everyone attacked me! Some of the items will move if I push into them, and others are immobile and block movement.
Just so you know, gamesas tech support suggestion for me in reference to the stuck quest books in inventory and the broken quest giver is to clear the HDD cache. Also, they cannot issue refunds and suggest going back to the original retailer...
This new character has 100 skill ranks in; archery, blacksmithing, enchanting, and alchemy. 94 in sneak, 70+ in illusion, 68 in speach, 55 in pickpocket, etc with around 100 game hours. FML.

*Trying to buy all the items cleared up a lot of the mess, but there are still things stuck in the air that won't move but block movement.