Dawnguard is in one word - fantastic! I liked the story and all the new characters, places and conversations. After I solved the entire DLC , I kinda was sad there isn't any more DLC story to go for since I loved owning some nasty vampires. It sure was worth 20$, though it could of been optimized better, so here are the problems I saw...

BUGS/GLITCHES/PROBLEMS :

-Werewolf killing animation sometime freezes, making the werewolf just stand there while the sound goes on as if he's actually killing the NPC. Then he goes back to his normal way.

-Breezehome Alchemy Table purchase is unavailable. You can use the option to purchase it, but you will never get it.

-Crossbow Bolts are not sticking into targets. Most of the time, bolts aren't even touching the body or the tip is barelly inside it. They magically float on the body like they're using Neo's bullet stop from Matrix.

-Crossbow bolts are always in the right hand of a character when loading a game. Usually any action with the crossbow removes it.

-Crossbow bolts floating on player's back. This is my No.1 problem. As a new feature, it is so badly optimized. The bolts are glued to your crossbow so they move as your crossbow does even though they should be immobile on your back, and when you're crouching, the bolts on your back are floating so far away it just hurts my eyes. I can't play with any armor except the imperial one since it's the only one that kind of hides the floating. FIX IT!!!

-The "Sparks" destruction spell when used by NPCs and when they're killed is having a bugged sound. Meaning, the loop sparking sound is still playing even after the NPCs are dead.

-Marked For Death / Drain Vitality - Don't know how this could of gone through BETA and 1 month delay for PC. Simply, If you learn all 3 words of Drain Vitality before Marked for Death, then Marked for Death shout is unavailable to be learned. On the other way around if you learn fully Marked for Death before Drain Vitality, then you get 3 Drain Vitality shouts in your list of which 2 don't count. (For more info, visit the Elderscrolls wiki)

-This one could be a possible bug : Aela Totems of Hircine Quests. After 18 radiant quests I still did not receive the Totems of Hircine quest. I had to use the console to get the quest. Usually it always took me just 1-2 quests to receive the MQ of Aela. This time after 18 quests, I knew something wasn't right.

-Durnehviir - I don't know what is he doing, though when I summon him in the middle of the battle... he is shouting at me. I'm not sure if his shout is supposed to heal me or give me stamina or if he's trying to kill me. I'd like some info on this

So those are the few problems I noticed during 4 days of playing. Overall Dawnguard is a great DLC, but it has a few problems that might annoy. The Vampire attacks also stopped for me after the Dawnguard MQ was complete so I'm glad it was done that way. Though, the Crossbow bolts floating on your back really needs fixing. It's so badly done. So the bottom line is, I'm happy with Dawnguard and looking forward for the next DLC that'll expand the Skyrim story further!

I liked it too, but I have two big gripes about it.

The issue with Serana is the way they characterized her and the dialogue options between her and the PC. People are led to believe that you can marry her at the end of the story-line, and then, suddenly, "no, I don't like temples."

I applaud Bethesda. Most impressive [censored] block indeed.

alot of people have made forums and stuff about the inability to marry Serana, and i agree with it for the most part. Its not so much the fact that i want to marry Serana but its more or less the Option. The Werewolf killing animation has done that before Dawnguard came out, they said it was fixed with the mounted combat patch but that really didnt work out. I have noticed the Crossbow's Bolts hovering on the back-waist of the player it is a bit annoying but you see your character from the back most of the time so you almost cant tell. Durnehviir shouting at you i have not had happen to me yet, he has shouted but its usually him summoning bonemen, wrathmen, or mistmen I have also seen him cast drain vitality or its Soul Tear im not to sure...Hope this helped

This is true, from the second you meet her the dialogue makes it out that she takes a shine to you, telling you intamite memories or thanking you for asking her about her feelings, then when the end of the questline comes the line "I will not let you hurt him/her" is said witch also makes you beleive some sort of feeling is there.

On some armors it isn't visible, but on armors like Dark Brotherhood and almost all light armors it floats so far away it's just silly
I think he was throwing Drain Vitality on me. Since he didn't summon any undead so it sure must be that. I'll have to check more to be sure.

It is silly lol i first noticed it wearing the Royal Vampire Armor, it hovers about a foot off your waist.